Electrochemical hydrogen pump

ABSTRACT

An electrochemical hydrogen pump includes: at least one hydrogen pump unit including an electrolyte membrane, an anode, a cathode, an anode separator, and a cathode separator; an anode end plate disposed on the anode separator positioned in a first end in a stacking direction, the first end is one end and the second end is another end; a cathode end plate disposed on the cathode separator positioned in a second end in the stacking direction; a fixing member that prevents at least members from the cathode end plate to the cathode separator positioned in the second end from moving in the stacking direction; a first gas flow channel through which hydrogen generated in the cathode is supplied to a first space disposed between the cathode end plate and the cathode separator positioned in the second end; and a first pressure transmitting member disposed in the first space.

BACKGROUND 1. Technical Field

The present disclosure relates to electrochemical hydrogen pumps.

2. Description of the Related Art

Hydrogen has recently attracted attention as a clean energy sourcealternative to fossil fuels from environmental problems such as globalwarming, and energy problems, such as depletion of petroleum resources.Hydrogen is expected as clean energy since hydrogen combustion basicallyreleases only water and releases no carbon dioxide, which causes globalwarming, and few nitrogen oxides and the like. Examples of devices usinghydrogen as a fuel at high efficiency include fuel cells. Fuel cells arebeing developed and spread for automotive power supplies and forself-power generation at home.

Coming hydrogen society needs, in addition to manufacture of hydrogen,development of techniques for storing hydrogen at high density andtransporting or using a small volume of hydrogen with low costs. Inparticular, the spreading and promotion of fuel cells serving asdistributed energy sources need construction of hydrogen supplyinfrastructure.

To stably supply hydrogen, various proposals for manufacturinghigh-purity hydrogen, refining hydrogen, and storing hydrogen at highdensity have been made.

For example, Japanese Unexamined Patent Application Publication No.2006-70322 (Patent Literature 1) proposes a high-pressure hydrogenmanufacturing apparatus in which a stack including a solid polymerelectrolyte membrane, a power supply member, and a separator is fastenedwith fastening bolts passing through end plates while the stack issandwiched between the end plates. In the high-pressure hydrogenmanufacturing apparatus, the solid polymer electrolyte membrane and ananode power supply member on the low pressure side deform when adifference in pressure between a cathode power supply member on the highpressure side and the anode power supply member on the low pressure sideis a predetermined pressure or more. In this case, the contactresistance between the cathode power supply member on the high pressureside and the solid polymer electrolyte membrane increases.

To solve this issue, the high-pressure hydrogen manufacturing apparatusdisclosed in Patent Literature 1 has a pressing unit, such as a discspring or a coil spring, that presses the cathode power supply member onthe high pressure side against the solid polymer electrolyte membrane sothat the cathode power supply member comes into close contact with thesolid polymer electrolyte membrane even if the solid polymer electrolytemembrane and the anode power supply member on the low pressure sidedeform. This configuration can suppress an increase in contactresistance between the cathode power supply member on the high pressureside and the solid polymer electrolyte membrane.

SUMMARY

However, in examples known in the related art, the increase of contactresistance between a cathode separator and a cathode has not beendiscussed well. One non-limiting and exemplary embodiment provides anelectrochemical hydrogen pump in which an increase in contact resistancebetween a cathode separator and a cathode in a hydrogen pump unit can beappropriately suppressed, compared with the related art.

In one general aspect, the techniques disclosed here feature anelectrochemical hydrogen pump including: at least one hydrogen pump unitthat includes an electrolyte membrane, an anode disposed on a first mainsurface of the electrolyte membrane, a cathode disposed on a second mainsurface of the electrolyte membrane, an anode separator stacked on theanode, and a cathode separator stacked on the cathode; an anode endplate that is disposed on the anode separator positioned in a first endin a stacking direction, the first end is one end in the stackingdirection and the second end is another end in the stacking direction; acathode end plate that is disposed on the cathode separator positionedin a second end in the stacking direction; a fixing member that preventsat least members from the cathode end plate to the cathode separatorpositioned in the second end from moving in the stacking direction; afirst gas flow channel through which hydrogen generated in the cathodeis supplied to a first space disposed between the cathode end plate andthe cathode separator positioned in the second end; and a first pressuretransmitting member that is disposed in the first space and transmits apressure from the cathode separator positioned in the second end to thecathode end plate.

The electrochemical hydrogen pump in one aspect of the presentdisclosure has an effect of appropriately suppressing an increase incontact resistance between the cathode separator and the cathode in thehydrogen pump unit, compared with the related art.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a view illustrating an example electrochemical hydrogen pump;

FIG. 1B is a view illustrating an example electrochemical hydrogen pump;

FIG. 2A is a view illustrating an example electrochemical hydrogen pumpaccording to a first embodiment;

FIG. 2B is an enlarged view of a section IIB in FIG. 2A;

FIG. 3A is a view illustrating an example electrochemical hydrogen pumpaccording to the first embodiment;

FIG. 3B is an enlarged view of a section IIIB in FIG. 3A;

FIG. 4A is a view illustrating an example electrochemical hydrogen pumpin Example 1 according to the first embodiment;

FIG. 4B is a view illustrating an example electrochemical hydrogen pumpin Example 2 according to the first embodiment;

FIG. 4C is a view illustrating an example electrochemical hydrogen pumpin Example 3 according to the first embodiment;

FIG. 4D is a view illustrating an example electrochemical hydrogen pumpin Example 4 according to the first embodiment;

FIG. 4E is a view illustrating an example electrochemical hydrogen pumpin Example 5 according to the first embodiment;

FIG. 5A is a view illustrating an example electrochemical hydrogen pumpin Modification 1 according to the first embodiment;

FIG. 5B is a view illustrating an example electrochemical hydrogen pumpin Modification 2 according to the first embodiment;

FIG. 5C is a view illustrating an example electrochemical hydrogen pumpin Modification 3 according to the first embodiment;

FIG. 6 is a view illustrating an example electrochemical hydrogen pumpaccording to a second embodiment;

FIG. 7 is a view illustrating an example electrochemical hydrogen pumpaccording to a third embodiment;

FIG. 8A is a view illustrating an example electrochemical hydrogen pumpin Example 1 according to the third embodiment;

FIG. 8B is a view illustrating an example electrochemical hydrogen pumpin Example 2 according to the third embodiment;

FIG. 8C is a view illustrating an example electrochemical hydrogen pumpin Example 3 according to the third embodiment;

FIG. 8D is a view illustrating an example electrochemical hydrogen pumpin Example 4 according to the third embodiment;

FIG. 8E is a view illustrating an example electrochemical hydrogen pumpin Example 5 according to the third embodiment;

FIG. 9A is a view illustrating an example electrochemical hydrogen pumpin Modification 1 according to the third embodiment;

FIG. 9B is a view illustrating an example electrochemical hydrogen pumpin Modification 2 according to the third embodiment;

FIG. 9C is a view illustrating an example electrochemical hydrogen pumpin Modification 3 according to the third embodiment; and

FIG. 10 is a view illustrating an example electrochemical hydrogen pumpaccording to a fourth embodiment.

DETAILED DESCRIPTION

In the high-pressure hydrogen manufacturing apparatus disclosed inPatent Literature 1, the stack is fastened with fastening bolts passingthrough the end plates and compressed in the stacking direction.However, the diligent studies carried out by the inventors of thepresent invention have found that, since the gas pressure of the cathodeis high, the cathode separator deforms so as to curve toward the endplate adjacent to the cathode separator, and the end plate accordinglydeforms so as to curve toward the outside which is a direction away fromthe stack. When there is a plurality of the stacks, the separatorspositioned in the ends in the stacking direction in the stacks deformtoward the end plates adjacent to the separators. With this deformation,the end plates also deform similarly.

As the cathode separator deforms, a larger gap than the gap described inthe paragraph [0020] in Patent Literature 1 is formed between thecathode separator and the cathode power supply member. To compensate forthis gap, the length of the disc spring that electrically couples thecathode power supply member to the cathode separator increases, and thedisc spring thus has large electrical resistance.

This feature is not limited to the high-pressure hydrogen manufacturingapparatus in Patent Literature 1 and applies to the electrochemicalhydrogen pump of the prior patent provided by the applicants asillustrated in FIG. 1A and FIG. 1B.

For example, as illustrated in FIG. 1A, it is proposed that a cathodegas diffusion layer 114 is stored in a recess of a cathode separator 116and protrudes from the recess by a predetermined amount Ecd in thethickness direction of the recess before a stack 500 is fastened. Thestack 500 includes an electrolyte membrane 111, a cathode catalyst layer112, an anode catalyst layer 113, the cathode gas diffusion layer 114,and an anode gas diffusion layer 115.

At this time, as illustrated in FIG. 1B, the cathode gas diffusion layer114 elastically deforms in the thickness direction by the amount ofprotrusion Ecd in fastening the stack 500.

During the operation of the electrochemical hydrogen pump, a highpressure is applied to the anode gas diffusion layer 115, the anodecatalyst layer 113, and the electrolyte membrane 111 when the gaspressure of the cathode gas diffusion layer 114 of the stack 500increases. Thus, the anode gas diffusion layer 115, the anode catalystlayer 113, and the electrolyte membrane 111 each undergo compressiondeformation. However, at this time, the contact between the cathodecatalyst layer 112 and the cathode gas diffusion layer 114 can beappropriately maintained by the elastic deformation of the cathode gasdiffusion layer 114 in the direction in which the thickness T2 aftercompression with the fastener returns to the thickness T1 beforecompression.

However, as described above, when the gas pressure of the cathodeincreases, the cathode separator 116 deforms so as to curve toward theend plate (outside) (not shown) adjacent to the cathode separator 116.In this case, a gap tends to be generated between the cathode gasdiffusion layer 114 and the bottom surface of the recess of the cathodeseparator 116, and the contact resistance between the cathode gasdiffusion layer 114 and the bottom surface of the recess of the cathodeseparator 116 may thus increase. As a result, the voltage applied by thevoltage applicator increases, which imposes a possibility that theoperation efficiency of the electrochemical hydrogen pump may decrease.

It is proposed that the increase of contact resistance between thecathode separator and the cathode when the gas pressure of the cathodeincreases in the electrochemical hydrogen pump of the prior patentprovided by the applicants is suppressed by providing a spacecommunicating with the cathode between the cathode separator and thecathode end plate disposed on the cathode separator.

In the case where a space communicating with the cathode is providedbetween the cathode separator and the cathode end plate disposed on thecathode separator, the increase of contact resistance between thecathode separator and the cathode is further studied, and the followingfindings are obtained.

For example, as illustrated in FIG. 1B, when the cathode gas diffusionlayer 114 elastically deforms in the thickness direction by the amountof protrusion Ecd in fastening the stack 500, the compression stress ofthe cathode gas diffusion layer 114 acts on the bottom surface of therecess of the cathode separator 116. At this time, the cathode separator116 fails to supply a high-pressure gas to the above-mentioned space(not shown) adjacent to the cathode separator 116, and the cathodeseparator 116 thus deforms so as to curve toward this space (outside).In this case, a gap tends to be generated between the cathode gasdiffusion layer 114 and the bottom surface of the recess of the cathodeseparator 116, and the contact resistance between the cathode gasdiffusion layer 114 and the bottom surface of the recess of the cathodeseparator 116 may thus increase. As a result, the voltage applied by thevoltage applicator increases, which imposes a possibility that theoperation efficiency of the electrochemical hydrogen pump may decrease.

The inventors of the present invention have found that the increase ofcontact resistance between the cathode separator and the cathode due tothe compression stress of the cathode acting on the cathode separatorcan be suppressed by disposing, in the above-mentioned space, a pressuretransmitting member that transmits the pressure from the cathodeseparator to the cathode end plate, compared with the case with nopressure transmitting member.

Specifically, the electrochemical hydrogen pump in one aspect of thepresent disclosure includes: at least one hydrogen pump unit thatincludes an electrolyte membrane, an anode disposed on a first mainsurface of the electrolyte membrane, a cathode disposed on a second mainsurface of the electrolyte membrane, an anode separator stacked on theanode, and a cathode separator stacked on the cathode; an anode endplate that is disposed on the anode separator positioned in a first endin a stacking direction, the first end is one end in the stackingdirection and the second end is another end in the stacking direction; acathode end plate that is disposed on the cathode separator positionedin a second end in the stacking direction; a fixing member that preventsat least members from the cathode end plate to the cathode separatorpositioned in the second end from moving in the stacking direction; afirst gas flow channel through which hydrogen generated in the cathodeis supplied to a first space disposed between the cathode end plate andthe cathode separator positioned in the second end; and a first pressuretransmitting member that is disposed in the first space and transmits apressure from the cathode separator positioned in the second end to thecathode end plate.

In the electrochemical hydrogen pump in this aspect having thisconfiguration, the increase of contact resistance between the cathodeseparator and the cathode in the hydrogen pump unit can be suppressedappropriately compared with the case with no pressure transmittingmember.

First, in the electrochemical hydrogen pump in this aspect, the increaseof contact resistance between the cathode separator and the cathode whenthe gas pressure of the cathode increases is suppressed in the followingmanner.

In the electrochemical hydrogen pump in this aspect, high-pressurehydrogen generated in the cathode of the hydrogen pump unit can besupplied to a first space disposed between the cathode end plate and thecathode separator through the first gas flow channel. Therefore, thehydrogen gas pressure in the first space is substantially the same asthe hydrogen gas pressure in the cathode of the hydrogen pump unit. Theload applied to the cathode separator by hydrogen in the first spaceacts so as to prevent or reduce the deformation (bending) of the cathodeseparator toward the cathode end plate due to the hydrogen gas pressurein the cathode.

If the cathode separator bends toward the cathode end plate, a gap tendsto be generated between the cathode separator and the cathode. When agap is generated between the cathode separator and the cathode, thecontact resistance between the cathode separator and the cathodeincreases.

However, in the electrochemical hydrogen pump in this aspect, the supplyof a high-pressure hydrogen gas to the first space disposed between thecathode end plate and the cathode separator, as described above, makesit difficult for the cathode separator to bend toward the cathode endplate. Since a gap is unlikely to form between the cathode separator andthe cathode of the hydrogen pump unit in the electrochemical hydrogenpump in this aspect compared with the case without the first space, theincrease of contact resistance between the cathode separator and thecathode can be suppressed appropriately.

Second, in the electrochemical hydrogen pump in this aspect, theincrease of contact resistance between the cathode separator and thecathode due to the compression stress of the cathode acting on thecathode separator can be suppressed in the following manner.

In the elastic deformation in the direction in which the thickness ofthe cathode decreases in the electrochemical hydrogen pump in thisaspect, the compression stress of the cathode acts in the direction inwhich the cathode separator is pressed toward the first space. If thefirst pressure transmitting member that transmits a pressure from thecathode separator to the cathode end plate is not disposed in the firstspace, the cathode separator tends to bend toward the cathode end plate.

If the cathode separator bends toward the cathode end plate, a gap tendsto be generated between the cathode separator and the cathode. When agap is generated between the cathode separator and the cathode, thecontact resistance between the cathode separator and the cathodeincreases.

However, in the electrochemical hydrogen pump in this aspect, thedisposition of, in the first space, the first pressure transmittingmember that transmits a pressure from the cathode separator to thecathode end plate, as described above, makes it difficult for thecathode separator to bend toward the cathode end plate in the elasticdeformation in the direction in which the thickness of the cathodedecreases. Since a gap is unlikely to form between the cathode separatorand the cathode of the hydrogen pump unit in the electrochemicalhydrogen pump in this aspect compared with the case without the firstpressure transmitting member in the first space, the increase of contactresistance between the cathode separator and the cathode can besuppressed appropriately.

According to an electrochemical hydrogen pump in a second aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the first aspect that may further include a cathode plate memberdisposed between the cathode end plate and the cathode separatorpositioned in the second end, wherein the first pressure transmittingmember may be disposed between the cathode end plate and the cathodeplate member and may include a columnar member separated from orintegrated with the cathode end plate.

According to this configuration, the first space between the cathode endplate and the cathode plate member in the electrochemical hydrogen pumpin this aspect enables the pressure from the cathode plate member to beappropriately transmitted to the cathode end plate through the columnarmember separated from or integrated with the cathode end plate.

According to an electrochemical hydrogen pump in a third aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the second aspect in which the fixing member may include a bolt, andthe bolt may pass through the cathode plate member and the cathodeseparator positioned in the second end.

In the electrochemical hydrogen pump in this aspect, this configurationreduces the displacement of the first space in the plane directioncaused as a result of the deformation of the cathode separatorpositioned in the second end in the stacking direction.

According to an electrochemical hydrogen pump in a fourth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the second aspect in which the cathode plate member may include acathode insulating plate, and the columnar member may be disposedbetween the cathode end plate and the cathode insulating plate.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the cathode insulating plate to beappropriately transmitted to the cathode end plate through the columnarmember disposed between the cathode end plate and the cathode insulatingplate.

According to an electrochemical hydrogen pump in a fifth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the second aspect in which the cathode plate member may include acathode power supply plate, and the columnar member may be disposedbetween the cathode end plate and the cathode power supply plate.According to an electrochemical hydrogen pump in a sixth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the fifth aspect in which the columnar member may be an insulatingmember.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the cathode power supply plate to beappropriately transmitted to the cathode end plate through theinsulating columnar member disposed between the cathode end plate andthe cathode power supply plate.

According to an electrochemical hydrogen pump in a seventh aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the first aspect in which the first pressure transmitting member mayinclude a porous member.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the cathode separator to be appropriatelytransmitted to the cathode end plate through the porous member disposedin the first space.

In the electrochemical hydrogen pump in this aspect, the use of theporous member as the first pressure transmitting member canappropriately ensure gas permeability in the first space, for example,even when the porous member is disposed in substantially the entireregion in the first space.

According to an electrochemical hydrogen pump in an eighth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the first aspect in which the first pressure transmitting member mayinclude an elastic member.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the cathode separator to be appropriatelytransmitted to the cathode end plate through the elastic member disposedin the first space.

In the electrochemical hydrogen pump in this aspect including theelastic member as the first pressure transmitting member, the elasticmember may conform to the deformation of the cathode separator if thecathode separator undergoes deformation due to the compression stress ofthe cathode. As a result, the pressure from the cathode separator isuniformly transmitted to the cathode end plate through the elasticmember.

According to an electrochemical hydrogen pump in a ninth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the first aspect in which the fixing member may further preventmembers from the anode end plate to the anode separator positioned inthe first end from moving in the stacking direction, and theelectrochemical hydrogen pump in the first aspect may further include: asecond gas flow channel through which hydrogen generated in the cathodeis supplied to a second space disposed between the anode end plate andthe anode separator positioned in the first end; and a second pressuretransmitting member that is disposed in the second space and transmits apressure from the anode separator positioned in the first end to theanode end plate.

In the electrochemical hydrogen pump in this aspect having thisconfiguration, the increase of contact resistance between the cathodeand the electrolyte membrane in the hydrogen pump unit when the gaspressure of the cathode increases is suppressed in the following manner.

On the basis of the hydrogen gas pressure in the cathode of the hydrogenpump unit, a load is transmitted to the anode and the anode separator.When the hydrogen gas pressure in the cathode of the hydrogen pump unitis high, the anode separator may be deformed by being pressed outwardunder this load. If the elastic deformation in the direction in whichthe thickness of the cathode increases cannot conform to the deformationof the anode separator, a gap may be generated between the cathode andthe electrolyte membrane of the hydrogen pump unit. As a result, thecontact resistance between the cathode and the electrolyte membrane ofthe hydrogen pump unit may increase.

However, in the electrochemical hydrogen pump in this aspect,high-pressure hydrogen generated in the cathode of the hydrogen pumpunit can be supplied to the second space disposed between the anode endplate and the anode separator through the second gas flow channel.Therefore, the hydrogen gas pressure in the second space issubstantially as high as the hydrogen gas pressure in the cathode of thehydrogen pump unit. The load applied to the anode separator by hydrogenin the second space acts so as to prevent or reduce the deformation ofthe anode separator due to the hydrogen gas pressure in the cathode.Since a gap is unlikely to form between the cathode and the electrolytemembrane of the hydrogen pump unit in the electrochemical hydrogen pumpin this aspect compared with the case without the second space, theincrease of contact resistance between the cathode and the electrolytemembrane can be suppressed appropriately.

In the electrochemical hydrogen pump in this aspect, the increase ofcontact resistance between the cathode and the electrolyte membrane ofthe hydrogen pump unit due to the compression stress of the cathodeacting on the anode separator can be suppressed in the following manner.

In the elastic deformation in the direction in which the thickness ofthe cathode decreases, the compression stress of the cathode acts in thedirection in which the anode separator is pressed toward the secondspace through the electrolyte membrane. If the second pressuretransmitting member that transmits a pressure from the anode separatorto the anode end plate is not disposed in the second space, the anodeseparator tends to bend toward the anode end plate. If the elasticdeformation in the direction in which the thickness of the cathodeincreases cannot conform to the deformation of the anode separator, agap may be generated between the cathode and the electrolyte membrane ofthe hydrogen pump unit. As a result, the contact resistance between thecathode and the electrolyte membrane of the hydrogen pump unit mayincrease.

However, in the electrochemical hydrogen pump in this aspect, thedisposition of, in the second space, the second pressure transmittingmember that transmits a pressure from the anode separator to the anodeend plate, as described above, makes it difficult for the anodeseparator to bend toward the anode end plate in the elastic deformationin the direction in which the thickness of the cathode decreases. Sincea gap is unlikely to form between the cathode and the electrolytemembrane of the hydrogen pump unit in the electrochemical hydrogen pumpin this aspect compared with the case without the second pressuretransmitting member in the second space, the increase of contactresistance between the cathode and the electrolyte membrane can besuppressed appropriately.

According to an electrochemical hydrogen pump in a tenth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the ninth aspect that may further include an anode plate memberdisposed between the anode end plate and the anode separator positionedin the first end, wherein the second pressure transmitting member may bedisposed between the anode end plate and the anode plate member and mayinclude a columnar member separated from or integrated with the anodeend plate.

According to this configuration, the second space between the anode endplate and the anode plate member in the electrochemical hydrogen pump inthis aspect enables the pressure from the anode plate member to beappropriately transmitted to the cathode end plate through the columnarmember separated from or integrated with the anode end plate.

According to an electrochemical hydrogen pump in an eleventh aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in the tenth aspect in which a bolt included in the fixing membermay pass through the anode plate member and the anode separatorpositioned in the first end.

In the electrochemical hydrogen pump in this aspect, this configurationreduces the displacement of the second space in the plane directioncaused as a result of the deformation of the anode separator positionedin the first end in the stacking direction.

According to an electrochemical hydrogen pump in a twelfth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the tenth aspect in which the anode plate member may include an anodeinsulating plate, and the columnar member may be disposed between theanode end plate and the anode insulating plate.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the anode insulating plate to be appropriatelytransmitted to the anode end plate through the columnar member disposedbetween the anode end plate and the anode insulating plate.

According to an electrochemical hydrogen pump in a thirteenth aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in the tenth aspect in which the anode plate member may include ananode power supply plate, and the columnar member may be disposedbetween the anode end plate and the anode power supply plate. Accordingto an electrochemical hydrogen pump in a fourteenth aspect of thepresent disclosure, there is provided the electrochemical hydrogen pumpin the thirteenth aspect in which the columnar member may be aninsulating member.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the anode power supply plate to beappropriately transmitted to the anode end plate through the insulatingcolumnar member disposed between the anode end plate and the anode powersupply plate.

According to an electrochemical hydrogen pump in a fifteenth aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in the ninth aspect in which the second pressure transmittingmember may include a porous member.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the anode separator to be appropriatelytransmitted to the anode end plate through the porous member disposed inthe second space.

In the electrochemical hydrogen pump in this aspect, the use of theporous member as the second pressure transmitting member canappropriately ensure gas permeability in the second space, for example,even when the porous member is disposed in substantially the entireregion in the second space.

According to an electrochemical hydrogen pump in a sixteenth aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in the ninth aspect in which the second pressure transmittingmember may include an elastic member.

In the electrochemical hydrogen pump in this aspect, this configurationenables the pressure from the anode separator to be appropriatelytransmitted to the anode end plate through the elastic member disposedin the second space.

In the electrochemical hydrogen pump in this aspect including theelastic member as the second pressure transmitting member, the elasticmember may conform to the deformation of the anode separator even if theanode separator is deformed by the compression stress of the cathode. Asa result, the pressure from the anode separator is uniformly transmittedto the anode end plate through the elastic member.

According to an electrochemical hydrogen pump in a seventeenth aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in any one of the first to sixteenth aspects in which the anode mayinclude an anode gas diffusion layer, the cathode may include a cathodegas diffusion layer, and the anode gas diffusion layer may have a higherelastic modulus than the cathode gas diffusion layer.

According to an electrochemical hydrogen pump in an eighteenth aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in the first aspect in which the first pressure transmitting membermay have the same elastic modulus as the cathode gas diffusion layerincluded in the cathode.

In the electrochemical hydrogen pump in this aspect having thisconfiguration, the deformation of the cathode separator due to thecompression stress of the cathode gas diffusion layer is suppressed bythe reaction force generated by the elastic deformation that occurs inthe direction in which the thickness of the first pressure transmittingmember having the same elastic modulus as the cathode gas diffusionlayer decreases. In other words, the amount of elastic deformation ofthe cathode gas diffusion layer is substantially equal to the amount ofelastic deformation of the first pressure transmitting member. Theforegoing reaction force can be thus maintained appropriately when thecathode gas diffusion layer elastically deforms in the direction inwhich the thickness after compression returns to the thickness beforecompression as the hydrogen pressure increasing operation of theelectrochemical hydrogen pump proceeds.

According to an electrochemical hydrogen pump in a nineteenth aspect ofthe present disclosure, there is provided the electrochemical hydrogenpump in the ninth aspect in which the second pressure transmittingmember may have the same elastic modulus as the cathode gas diffusionlayer included in the cathode.

In the electrochemical hydrogen pump in this aspect having thisconfiguration, the deformation of the anode separator due to thecompression stress of the cathode gas diffusion layer is suppressed bythe reaction force generated by the elastic deformation that occurs inthe direction in which the thickness of the second pressure transmittingmember having the same elastic modulus as the cathode gas diffusionlayer decreases. In other words, the amount of elastic deformation ofthe cathode gas diffusion layer is substantially equal to the amount ofelastic deformation of the second pressure transmitting member. Theforegoing reaction force can be thus maintained appropriately when thecathode gas diffusion layer elastically deforms in the direction inwhich the thickness after compression returns to the thickness beforecompression as the hydrogen pressure increasing operation of theelectrochemical hydrogen pump proceeds.

According to an electrochemical hydrogen pump, there is provided atwentieth aspect of the present disclosure is the electrochemicalhydrogen pump in the first aspect in which the fixing member may be afastener that fastens at least one hydrogen pump unit sandwiched betweenthe anode end plate and the cathode end plate.

Embodiments of the present disclosure will be described below withreference to the accompanying drawings. The embodiments described belowillustrate examples of the aspects described above. The shapes,materials, and components, and the arrangement positions and connectionconfiguration of the components described below are illustrative onlyand should not be construed as limiting the aspects unless otherwisementioned in Claims. Among the components described below, thecomponents that are not mentioned in independent claims indicating thebroadest concepts of the aspects are described as optional components.Redundant description of the components assigned with the same referencecharacters in the drawings may be avoided. Each component isschematically illustrated in the drawings for easy understanding, andthe shape, the dimensional ratio, and the like may not be accuratelydepicted.

First Embodiment

Apparatus Structure

FIG. 2A and FIG. 3A are views illustrating example electrochemicalhydrogen pumps according to the first embodiment. FIG. 2B is an enlargedview of a section IIB in FIG. 2A. FIG. 3B is an enlarged view of asection IIIB in FIG. 3A.

FIG. 2A illustrates the vertical cross-section of an electrochemicalhydrogen pump 100 including a straight line that passes through thecenter of the electrochemical hydrogen pump 100 and the center of acathode gas outlet manifold 50 in plan view. FIG. 3A illustrates thevertical cross-section of the electrochemical hydrogen pump 100including a straight line that passes through the center of theelectrochemical hydrogen pump 100, the center of an anode gas inletmanifold 27, and the center of an anode gas outlet manifold 30 in planview.

In the examples illustrated in FIG. 2A and FIG. 3A, the electrochemicalhydrogen pump 100 includes at least one hydrogen pump unit 100A.

In the electrochemical hydrogen pumps 100 illustrated in FIG. 2A andFIG. 3A, three hydrogen pump units 100A are stacked on top of oneanother. The number of hydrogen pump units 100A is not limited to this.The number of hydrogen pump units 100A can be set to a suitable value onthe basis of the operating conditions, such as the amount of hydrogenwhose pressure is increased by the electrochemical hydrogen pump 100.

The hydrogen pump unit 100A includes an electrolyte membrane 11, ananode AN, a cathode CA, a cathode separator 16, an anode separator 17,and an insulator 21.

The anode AN is disposed in a first main surface of the electrolytemembrane 11. The anode AN is an electrode including an anode catalystlayer 13 and an anode gas diffusion layer 15 disposed on the anodecatalyst layer 13. In plan view, an annular seal member 43 is disposedso as to surround the periphery of the anode catalyst layer 13, and theanode catalyst layer 13 is appropriately sealed by the seal member 43.

The cathode CA is disposed in a second main surface of the electrolytemembrane 11. The cathode CA is an electrode including a cathode catalystlayer 12 and a cathode gas diffusion layer 14 disposed on the cathodecatalyst layer 12. In plan view, an annular seal member 42 is disposedso as to surround the periphery of the cathode catalyst layer 12, andthe cathode catalyst layer 12 is appropriately sealed by the seal member42.

Accordingly, the electrolyte membrane 11 is sandwiched between the anodeAN and the cathode CA in such a manner that the electrolyte membrane 11is in contact with the anode catalyst layer 13 and the cathode catalystlayer 12. A stack of the cathode CA, the electrolyte membrane 11, andthe anode AN is referred to as a membrane electrode assembly (MEA).

The electrolyte membrane 11 has proton conductivity. The electrolytemembrane 11 may be made of any material as long as it has protonconductivity. Examples of the electrolyte membrane 11 include, but arenot limited to, fluoropolymer electrolyte membranes and hydrocarbonpolymer electrolyte membranes. Specifically, for example, Nafion(registered trademark, available from DuPont) and Aciplex (registeredtrademark, available from Asahi Kasei Corporation) can be used as theelectrolyte membrane 11.

The anode catalyst layer 13 is disposed in the first main surface of theelectrolyte membrane 11. The anode catalyst layer 13 contains, forexample, platinum as a catalyst metal, but the catalyst metal is notlimited to platinum.

The cathode catalyst layer 12 is disposed in the second main surface ofthe electrolyte membrane 11. The cathode catalyst layer 12 contains, forexample, platinum as a catalyst metal, but the catalyst metal is notlimited to platinum.

Examples of the catalyst support in the cathode catalyst layer 12 andthe anode catalyst layer 13 include, but are not limited to, carbonpowders formed of, for example, carbon black and graphite; andelectrically conductive oxide powders.

In the cathode catalyst layer 12 and the anode catalyst layer 13, thefine particles of the catalyst metal are highly dispersed and supportedon the catalyst support. The cathode catalyst layer 12 and the anodecatalyst layer 13 normally contain an ionomer component having hydrogenion conductivity in order to increase the electrode reaction area.

The anode gas diffusion layer 15 is formed of a porous material and haselectrical conductivity and gas diffusibility. The anode gas diffusionlayer 15 preferably has high rigidity so as to prevent or reducedisplacement and deformation of constituent members caused by adifference in pressure between the cathode CA and the anode AN duringoperation of the electrochemical hydrogen pump 100. In other words, theanode gas diffusion layer 15 has a higher elastic modulus than thecathode gas diffusion layer 14.

Examples of the base material of the anode gas diffusion layer 15include sintered products of metal fibers formed of titanium, titaniumalloys, stainless steel, and the like; and sintered products of metalpowders, expanded metals, metal meshes, and punched metals formed ofthese materials.

The cathode gas diffusion layer 14 is formed of a porous material andhas electrical conductivity and gas diffusibility. The cathode gasdiffusion layer 14 preferably has elasticity so as to appropriatelyconform to displacement and deformation of constituent members caused bya difference in pressure between the cathode and the anode duringoperation of the electrochemical hydrogen pump 100. In other words, thecathode gas diffusion layer 14 has a lower elastic modulus than theanode gas diffusion layer 15.

Examples of the base material of the cathode gas diffusion layer 14include sintered products of metal fibers formed of titanium, titaniumalloys, stainless steel, and the like; and sintered products of metalpowders, expanded metals, metal meshes, and punched metals formed ofthese materials. Examples of the base material of the cathode gasdiffusion layer 14 include porous carbon materials, such as carbonpaper, carbon cloth, and carbon felt. Moreover, for example, poroussheet materials formed by kneading carbon black and an elastomer such asPTFE and rolling the kneaded material can also be used.

The anode separator 17 is a member stacked on the anode AN. The cathodeseparator 16 is a member stacked on the cathode CA. The cathodeseparator 16 and the anode separator 17 each have a recess in theircentral portion. The cathode gas diffusion layer 14 and the anode gasdiffusion layer 15 are stored in the respective recesses.

Accordingly, the hydrogen pump unit 100A is formed by sandwiching theMEA between the cathode separator 16 and the anode separator 17.

In plan view, for example, a serpentine cathode gas flow channel 32including a plurality of U-shaped curved portions and a plurality oflinear portions is provided in the main surface of the cathode separator16 in contact with the cathode gas diffusion layer 14. The linearportions of the cathode gas flow channel 32 extend in the directionperpendicular to the plane of FIG. 2A. However, the cathode gas flowchannel 32 is illustrative, and the present invention is not limited tothis example. For example, the cathode gas flow channel may include aplurality of linear flow channels.

In plan view, for example, a serpentine anode gas flow channel 33including a plurality of U-shaped curved portions and a plurality oflinear portions is provided in the main surface of the anode separator17 in contact with the anode gas diffusion layer 15. The linear portionsof the anode gas flow channel 33 extend in the direction perpendicularto the plane of FIG. 3A. However, the anode gas flow channel 33 isillustrative, and the present invention is not limited to this example.For example, the anode gas flow channel may include a plurality oflinear flow channels.

An annular and plate-shaped insulator 21 is sandwiched between thecathode separator 16 and the anode separator 17 each having electricalconductivity. The insulator 21 surrounds the periphery of the MEA. Thisconfiguration avoids the short circuit between the cathode separator 16and the anode separator 17.

As illustrated in FIG. 2A and FIG. 3A, the electrochemical hydrogen pump100 includes an anode end plate 24A and a cathode end plate 24C.

The anode end plate 24A is a member disposed on the anode separator 17positioned in the first end of the electrochemical hydrogen pump 100 inthe stacking direction of the members of the hydrogen pump unit 100A.The anode separator 17 positioned in the first end of theelectrochemical hydrogen pump 100 is, namely, the anode separator 17positioned closest to the anode end plate 24A. In addition, the cathodeend plate 24C is a member disposed on the cathode separator 16positioned in the second end of the electrochemical hydrogen pump 100 inthe stacking direction of the members of the hydrogen pump unit 100A.The cathode separator 16 positioned in the second end of theelectrochemical hydrogen pump 100 is, namely, the cathode separator 16positioned closest to the cathode end plate 24C.

As illustrated in FIG. 2A and FIG. 3A, the electrochemical hydrogen pump100 includes a fixing member that prevents at least members from thecathode end plate 24C to the cathode separator 16 positioned in thesecond end of the electrochemical hydrogen pump 100 from moving in thestacking direction of the members of the hydrogen pump unit 100A.

The members of the hydrogen pump unit 100A correspond to the electrolytemembrane 11, the anode AN, the cathode CA, the anode separator 17, andthe cathode separator 16. Members from the cathode end plate 24C to thecathode separator 16 positioned in the second end correspond to thecathode end plate 24C, the cathode separator 16 positioned in the secondend, and the members stacked between the cathode end plate 24C and thecathode separator 16 positioned in the second end. In this embodiment,specifically, the members from the cathode end plate 24C to the cathodeseparator 16 positioned in the second end correspond to the cathode endplate 24C, a cathode insulating plate 23C, a cathode power supply plate22C, and the cathode separator 16 positioned in the second end.

The fixing member may have any structure as long as it can fix, in thestacking direction of the members of the hydrogen pump unit 100A, atleast the members from the cathode end plate 24C to the cathodeseparator 16 positioned in the second end of the electrochemicalhydrogen pump 100. For example, as illustrated in FIG. 2A and FIG. 3A,the fixing member may be a fastener 25 that fastens at least onehydrogen pump unit 100A sandwiched between the anode end plate 24A andthe cathode end plate 24C. Examples of the fastener 25 include a boltand a disc spring nut.

In this case, the bolts of the fastener 25 may pass through only theanode end plate 24A and the cathode end plate 24C.

In the electrochemical hydrogen pump 100 according to this embodiment,however, the bolts of the fastener 25 pass through, in addition to theanode end plate 24A and the cathode end plate 24C, the members of thehydrogen pump unit 100A, a cathode plate member 80C disposed between thecathode end plate 24C and the cathode separator 16 positioned in thesecond end, and an anode plate member 80A disposed between the anode endplate 24A and the anode separator 17 positioned in the first end.

The fastener 25 applies a desired fastening pressure to the hydrogenpump unit 100A in such a manner that the end surface of the cathodeseparator 16 positioned in the second end of the electrochemicalhydrogen pump 100 in the stacking direction and the end surface of theanode separator 17 positioned in the first end of the electrochemicalhydrogen pump 100 in the stacking direction are sandwiched between thecathode end plate 24C and the anode end plate 24A, with the cathodeplate member 80C interposed between the cathode separator 16 and thecathode end plate 24C and the anode plate member 80A interposed betweenthe anode separator 17 and the anode end plate 24A.

In other words, in this embodiment, the fixing member further prevents,in addition to the members from the cathode end plate 24C to the cathodeseparator 16 positioned in the second end of the electrochemicalhydrogen pump 100, and members from the anode end plate 24A to the anodeseparator 17 positioned in the first end of the electrochemical hydrogenpump 100 from moving in the stacking direction of the members of thehydrogen pump unit 100A. The members from the anode end plate 24A to theanode separator 17 positioned in the first end of the electrochemicalhydrogen pump 100 correspond to the anode end plate 24A, the anodeseparator 17 positioned in the first end, the members stacked betweenthe anode end plate 24A and the anode separator 17 positioned in thefirst end. In this embodiment, specifically, and the members from theanode end plate 24A to the anode separator 17 positioned in the firstend correspond to the anode end plate 24A, an anode insulating plate23A, an anode power supply plate 22A, and the anode separator 17positioned in the first end.

The cathode plate member 80C is, for example, a member including thecathode power supply plate 22C and the cathode insulating plate 23C. Theanode plate member 80A is, for example, a member including the anodepower supply plate 22A and the anode insulating plate 23A.

Accordingly, three hydrogen pump units 100A are appropriately maintainedin the stacked state by means of the fastening pressure of the fastener25 while the bolts of the fastener 25 pass through the cathode platemember 80C, the cathode separator 16 closest to the cathode plate member80C, the anode plate member 80A, and the anode separator 17 closest tothe anode plate member 80A. Since the bolts included in the fastener 25pass through the cathode plate member 80C and the anode plate member80A, the cathode plate member 80C and the anode plate member 80A can beappropriately prevented from moving in the in-plane direction. Thisconfiguration reduces the displacement of a first space 60 in the planedirection (described below) caused as a result of the deformation of thecathode separator 16 positioned in the second end in the stackingdirection. This configuration also reduces the displacement of a secondspace 65 in the plane direction (described below) caused as a result ofthe deformation of the anode separator 17 positioned in the first end ofthe electrochemical hydrogen pump 100 in the stacking direction.

Although detailed description and illustration are omitted here, insteadof using the fastener 25, the electrochemical hydrogen pump may be fixedby disposing a seal material made of resin on the side surfaces of themembers of the electrochemical hydrogen pump.

As illustrated in FIG. 2A and FIG. 3A, the electrochemical hydrogen pump100 includes a first gas flow channel through which hydrogen generatedin the cathode CA is supplied to the first space 60 disposed between thecathode end plate 24C and the cathode separator 16 positioned in thesecond end.

The first space 60 has any feature as long as the first space 60 isdisposed between the cathode end plate 24C and the cathode separator 16positioned in the second end. In the examples illustrated in FIG. 2A andFIG. 3A, the first space 60 is formed by a recess in a central portionof the cathode end plate 24C. In other words, the first space 60 isdefined by the recess in the central portion of the cathode end plate24C and the cathode insulating plate 23C. Other examples of the firstspace will be described in Modifications.

In the electrochemical hydrogen pump 100 according to this embodiment,the first pressure transmitting member is provided in the first space 60as indicated by the arrows in FIG. 2A and FIG. 3A. The first pressuretransmitting member may have any structure as long as it can transmit apressure from the cathode separator 16 positioned in the second end tothe cathode end plate 24C. Specific structures of the first pressuretransmitting member will be described in Examples.

The first gas flow channel may have any structure as long as hydrogengenerated in the cathode CA can be supplied to the first space 60through the first gas flow channel. For example, in the electrochemicalhydrogen pump 100 according to this embodiment, as illustrated in FIG.2A, the first gas flow channel includes a tubular cathode gas outletmanifold 50 and a cathode gas supply channel 51 through which thecathode gas outlet manifold 50 is in communication with the first space60.

The cathode gas outlet manifold 50 is formed by connection ofthrough-holes in the members of the hydrogen pump unit 100A andnon-through holes in the anode end plate 24A and the cathode end plate24C.

The cathode gas supply channel 51 is formed by a groove that is providedin the main surface of the cathode end plate 24C and through which theinside of the recess (first space 60) of the cathode end plate 24C is incommunication with a second end portion of the cathode gas outletmanifold 50.

As illustrated in FIG. 2A, a cathode gas outlet channel 26 is disposedin the cathode end plate 24C. The cathode gas outlet channel 26 may beformed by a pipe through which hydrogen (H2) discharged from the cathodeCA flows. The cathode gas outlet channel 26 is in communication with thefirst space 60. Accordingly, the cathode gas outlet channel 26 is incommunication with the cathode gas outlet manifold 50 through the firstspace 60 and the cathode gas supply channel 51.

The cathode gas outlet manifold 50 is in communication with a first endportion of the cathode gas flow channel 32 of each hydrogen pump unit100A through the corresponding cathode gas passage 34. In other words,in the electrochemical hydrogen pump 100 according to this embodiment,the cathode gas flow channels 32 are in communication with each other.The cathode gas leaving the cathode gas diffusion layer 14 of eachhydrogen pump unit 100A flows through the corresponding cathode gas flowchannel 32. Accordingly, hydrogen flows that have passed through thecathode gas flow channels 32 and the cathode gas passages 34 of therespective hydrogen pump units 100A merge in the cathode gas outletmanifold 50. The merged hydrogen flow passes through the cathode gassupply channel 51 and the first space 60 in this order and is guided tothe cathode gas outlet channel 26. High-pressure hydrogen flows throughthe first space 60 accordingly.

In plan view, annular seal members 40, such as O-rings, are disposedbetween the cathode separator 16 and the anode separator 17, between thecathode separator 16 and the cathode power supply plate 22C, and betweenthe anode separator 17 and the anode power supply plate 22A so as tosurround the cathode gas outlet manifold 50. The cathode gas outletmanifold 50 is appropriately sealed by the seal members 40.

As illustrated in FIG. 3A, an anode gas inlet channel 29 is provided inthe anode end plate 24A. The anode gas inlet channel 29 may be formed bya pipe through which hydrogen (H2) supplied to the anode AN flows. Theanode gas inlet channel 29 is in communication with the tubular anodegas inlet manifold 27. The anode gas inlet manifold 27 is formed byconnection of through-holes in the members of the hydrogen pump unit100A and the anode end plate 24A.

The anode gas inlet manifold 27 is in communication with the first endportion of the anode gas flow channel 33 of each hydrogen pump unit 100Athrough the corresponding first anode gas passage 35. The hydrogensupplied to the anode gas inlet manifold 27 from the anode gas inletchannel 29 is thus distributed to the hydrogen pump units 100A throughthe first anode gas passages 35 of the hydrogen pump units 100A. Whilethe distributed hydrogen passes thorough the anode gas flow channels 33,hydrogen is supplied to the anode catalyst layers 13 from the anode gasdiffusion layers 15.

As illustrated in FIG. 3A, an anode gas outlet channel 31 is provided inthe anode end plate 24A. The anode gas outlet channel 31 may be formedby a pipe through which hydrogen (H2) discharged from the anode ANflows. The anode gas outlet channel 31 is in communication with thetubular anode gas outlet manifold 30. The anode gas outlet manifold 30is formed by connection of through-holes in the members of the hydrogenpump unit 100A and the anode end plate 24A.

The anode gas outlet manifold 30 is in communication with a second endportion of the anode gas flow channel 33 of each hydrogen pump unit 100Athrough the corresponding second anode gas passage 36. Accordingly,hydrogen flows that have passed through the anode gas flow channels 33of the hydrogen pump units 100A are supplied to the anode gas outletmanifold 30 through the respective second anode gas passages 36 andmerge in the anode gas outlet manifold 30. The merged hydrogen flow isguided to the anode gas outlet channel 31.

In plan view, annular seal members 40, such as O-rings, are disposedbetween the cathode separator 16 and the anode separator 17, between thecathode separator 16 and the cathode power supply plate 22C, and betweenthe anode separator 17 and the anode power supply plate 22A so as tosurround the anode gas inlet manifold 27 and the anode gas outletmanifold 30. The anode gas inlet manifold 27 and the anode gas outletmanifold 30 are appropriately sealed by the seal members 40.

As illustrated in FIG. 2A and FIG. 3A, the electrochemical hydrogen pump100 includes a voltage applicator 102.

The voltage applicator 102 is a device that applies a voltage across theanode AN and the cathode CA. Specifically, a high potential of thevoltage applicator 102 is applied to the anode AN having electricalconductivity, and a low potential of the voltage applicator 102 isapplied to the cathode CA having electrical conductivity. The voltageapplicator 102 may have any structure as long as it can apply a voltageacross the anode AN and the cathode CA. For example, the voltageapplicator 102 may be a device that controls the voltage applied acrossthe anode AN and the cathode CA. In this case, the voltage applicator102 includes a DC/DC converter when connected to a direct-current powersupply, such as a battery, a solar cell, and a fuel cell, and includesan AC/DC converter when connected to an alternating-current powersupply, such as a commercial power supply.

The voltage applicator 102 may be, for example, an electric power-typepower supply that controls the voltage applied across the anode AN andthe cathode CA and the current flowing between the anode AN and thecathode CA in such a manner that the electric power supplied to thehydrogen pump unit 100A becomes a predetermined value.

In the examples illustrated in FIG. 2A and FIG. 3A, the terminal of thevoltage applicator 102 on the low-potential side is connected to thecathode power supply plate 22C, and the terminal of the voltageapplicator 102 on the high-potential side is connected to the anodepower supply plate 22A. The cathode power supply plate 22C is inelectrical contact with the cathode separator 16 positioned in thesecond end of the electrochemical hydrogen pump 100 in the stackingdirection. The anode power supply plate 22A is in electrical contactwith the anode separator 17 positioned in the first end of theelectrochemical hydrogen pump 100 in the stacking direction.

Although not shown, a hydrogen supply system including theelectrochemical hydrogen pump 100 can be constructed. In this case, adevice required for the hydrogen supply operation of the hydrogen supplysystem is provided as needed.

For example, the hydrogen supply system may include a dew-pointcontroller (e.g., humidifier) that controls the dew point of a gasmixture of high-humidity hydrogen (H2) discharged from the anode ANthrough the anode gas outlet channel 31 and low-humidity hydrogen (H2)supplied from an external hydrogen supply source through the anode gasinlet channel 29. In this case, hydrogen from the external hydrogensupply source may be, for example, generated in a water electrolysisdevice.

The hydrogen supply system may include, for example, a temperaturesensor that senses the temperature of the electrochemical hydrogen pump100; a hydrogen reservoir that temporarily stores hydrogen dischargedfrom the cathode CA of the electrochemical hydrogen pump 100; and apressure sensor that senses the hydrogen gas pressure in the hydrogenreservoir.

The structure of the electrochemical hydrogen pump 100 and variousdevices (not shown) in the hydrogen supply system are illustrative, andthe present invention is not limited to this example.

For example, a dead-end structure in which the pressure of the totalhydrogen supply to the anode AN through the anode gas inlet manifold 27is increased in the cathode CA may be employed without providing theanode gas outlet manifold 30 and the anode gas outlet channel 31. Forexample, hydrogen (H2) flows through the anode gas flow channel 33 andthe cathode gas flow channel 32 as described above, but the hydrogenconcentration is not necessarily 100%. A hydrogen-containing gas mayflow.

Operation

An example of the hydrogen pressure increasing operation of theelectrochemical hydrogen pump 100 will be described below with referenceto the drawings.

The following operation may be performed by, for example, an arithmeticcircuit of a controller (not shown) reading a control program from amemory circuit of the controller. However, the following operation isnot necessarily performed by the controller. An operator may operatepart of the operation.

First, low-pressure hydrogen is supplied to the anode AN of theelectrochemical hydrogen pump 100, and the voltage of the voltageapplicator 102 is applied to the electrochemical hydrogen pump 100.

In the anode catalyst layer 13 of the anode AN, a hydrogen moleculedissociates into hydrogen ions (protons) and electrons in the oxidationreaction (formula (1)). The protons are conducted through theelectrolyte membrane 11 and transferred to the cathode catalyst layer12. The electrons are transferred to the cathode catalyst layer 12through the voltage applicator 102.

In the cathode catalyst layer 12, a hydrogen molecule is generated againin the reduction reaction (formula (2)). It is known that apredetermined amount of water serving as electroosmosis water istransferred from the anode AN to the cathode CA together with protonswhen protons are conducted through the electrolyte membrane 11.

At this time, the pressure of hydrogen (H2) generated in the cathode CAcan be increased by raising the pressure drop of a hydrogen outletchannel by using a flow rate controller (not shown). High-pressurehydrogen generated in the cathode CA is thus supplied to the first space60 between the cathode end plate 24C and the cathode separator 16through the cathode gas outlet manifold 50 and the cathode gas supplychannel 51. Examples of the hydrogen outlet channel include the cathodegas outlet channel 26 in FIG. 2A. Examples of the low rate controllerinclude a back pressure valve and a regulator valve, which are providedat the hydrogen outlet channel.Anode:H2(low pressure)→2H++2e−  (1)Cathode:2H++2e→H2(high pressure)  (2)

In the electrochemical hydrogen pump 100, the pressure of hydrogensupplied to the anode AN is thus increased in the cathode CA byapplication of a voltage with the voltage applicator 102. The hydrogenpressure increasing operation of the electrochemical hydrogen pump 100is performed accordingly, and the hydrogen whose pressure has beenincreased in the cathode CA is, for example, temporarily stored in ahydrogen reservoir (not shown). The hydrogen stored in the hydrogenreservoir is supplied to a hydrogen receptor at suitable timing.Examples of the hydrogen receptor include fuel cells which generateelectric power by using hydrogen.

In the hydrogen pressure increasing operation of the electrochemicalhydrogen pump 100, the gas pressure of the cathode CA increases, whichpresses the electrolyte membrane 11, the anode catalyst layer 13, andthe anode gas diffusion layer 15. This pressing compresses each of theelectrolyte membrane 11, the anode catalyst layer 13, and the anode gasdiffusion layer 15.

If the adhesion between the cathode catalyst layer 12 and the cathodegas diffusion layer 14 is low at this time, a gap tends to be generatedbetween the cathode catalyst layer 12 and the cathode gas diffusionlayer 14. When a gap is generated between the cathode catalyst layer 12and the cathode gas diffusion layer 14, the contact resistance betweenthe cathode catalyst layer 12 and the cathode gas diffusion layer 14increases. As a result, the voltage applied by the voltage applicator102 increases, which imposes a possibility that the operation efficiencyof the electrochemical hydrogen pump 100 may decrease.

The cathode gas diffusion layer 14 protrudes from the recess of thecathode separator 16 by a desired amount of protrusion Ecd in thethickness direction of the recess before the hydrogen pump unit 100A isfastened with the fastener 25. The cathode gas diffusion layer 14 iscompressed with the fastening force of the fastener 25 by theabove-described amount of protrusion when the hydrogen pump unit 100A isfastened.

Accordingly, even if the electrolyte membrane 11, the anode catalystlayer 13, and the anode gas diffusion layer 15 each undergo compressiondeformation during the operation of the electrochemical hydrogen pump100, the contact between the cathode catalyst layer 12 and the cathodegas diffusion layer 14 can be appropriately maintained by the elasticdefamation of the cathode gas diffusion layer 14 in the direction inwhich the thickness after compression with the fastener 25 returns tothe original thickness before compression in the electrochemicalhydrogen pump 100 according to this embodiment.

In the electrochemical hydrogen pump 100 according to this embodiment,the increase of contact resistance between the cathode separator 16 andthe cathode CA in the hydrogen pump unit 100A may be appropriatelysuppressed, compared with the related art.

First, in the electrochemical hydrogen pump 100 according to thisembodiment, the increase of contact resistance between the cathodeseparator 16 and the cathode gas diffusion layer 14 when the gaspressure of the cathode CA increases is suppressed in the followingmanner.

In the electrochemical hydrogen pump 100 according to this embodiment,high-pressure hydrogen generated in the cathode CA of the hydrogen pumpunit 100A can be supplied to the first space 60 disposed between thecathode end plate 24C and the cathode insulating plate 23C through thecathode gas outlet manifold 50 and the cathode gas supply channel 51.Therefore, the hydrogen gas pressure in the first space 60 issubstantially the same as the hydrogen gas pressure in the cathode CA ofthe hydrogen pump unit 100A. The load applied to the cathode separator16 by hydrogen in the first space 60 acts so as to prevent or reduce thedeformation (bending) of the cathode separator 16 toward the cathode endplate 24C due to the hydrogen gas pressure in the cathode CA.

If the cathode separator 16 bends toward the cathode end plate 24C, agap tends to be generated between the cathode separator 16 and thecathode gas diffusion layer 14. When a gap is generated between thecathode separator 16 and the cathode gas diffusion layer 14, the contactresistance between the cathode separator 16 and the cathode gasdiffusion layer 14 increases.

However, in the electrochemical hydrogen pump 100 according to thisembodiment, the supply of a high-pressure hydrogen gas to the firstspace 60 disposed between the cathode end plate 24C and the cathodeinsulating plate 23C, as described above, makes it difficult for thecathode separator 16 to bend toward the cathode end plate 24C. Since agap is unlikely to form between the cathode separator 16 and the cathodegas diffusion layer 14 of the hydrogen pump unit 100A in theelectrochemical hydrogen pump 100 according to this embodiment comparedwith the case without the first space 60, the increase of contactresistance between the cathode separator 16 and the cathode gasdiffusion layer 14 can be suppressed appropriately.

Second, in the electrochemical hydrogen pump 100 according to thisembodiment, the increase of contact resistance between the cathodeseparator 16 and the cathode gas diffusion layer 14 due to thecompression stress of the cathode gas diffusion layer 14 acting on thecathode separator 16 can be suppressed in the following manner.

In the electrochemical hydrogen pump 100 according to this embodiment,the compression stress of the cathode gas diffusion layer 14 acts in thedirection in which the cathode separator 16 is pressed toward the firstspace 60 in the elastic deformation in the direction in which thecathode gas diffusion layer 14 decreases. If the first pressuretransmitting member that transmits a pressure from the cathode separator16 to the cathode end plate 24C is not disposed in the first space 60,the cathode separator 16 tends to bend toward the cathode end plate 24C.

If the cathode separator 16 bends toward the cathode end plate 24C, agap tends to be generated between the cathode separator 16 and thecathode gas diffusion layer 14. If a gap is generated between thecathode separator 16 and the cathode gas diffusion layer 14, the contactresistance between the cathode separator 16 and the cathode gasdiffusion layer 14 increases.

However, in the electrochemical hydrogen pump 100 according to thisembodiment, the disposition of, in the first space 60, the firstpressure transmitting member that transmits a pressure from the cathodeseparator 16 to the cathode end plate 24C, as described above, makes itdifficult for the cathode separator 16 to bend toward the cathode endplate 24C in the elastic deformation in the direction in which thethickness of the cathode gas diffusion layer 14 decreases. Since a gapis unlikely to form between the cathode separator 16 and the cathode gasdiffusion layer 14 of the hydrogen pump unit 100A in the electrochemicalhydrogen pump 100 according to this embodiment compared with the casewithout the first pressure transmitting member in the first space 60,the increase of contact resistance between the cathode separator 16 andthe cathode gas diffusion layer 14 can be suppressed appropriately.

In the examples illustrated in FIG. 2A and FIG. 3A, the first space 60is parallel to the main surface of the cathode CA in the electrochemicalhydrogen pump 100.

The load transmitted to the cathode separator 16 can be thus uniformlydistributed in the plane of the cathode separator 16 on the basis of thehydrogen gas pressure in the first space 60. Therefore, theelectrochemical hydrogen pump 100 according to this embodimenteffectively operates in such a manner that the load applied to thecathode separator 16 by hydrogen in the first space 60 prevents orreduces deformation (bending) of the cathode separator 16 compared withthe case where the first space 60 is not parallel to the main surface ofthe cathode CA.

In the examples illustrated in FIG. 2A and FIG. 3A, the opening area ofthe first space 60 in the direction parallel to the main surface of thecathode separator 16 in the electrochemical hydrogen pump 100 is largerthan or equal to the area of the main surface of the cathode CA.However, the opening area of such a first space 60 is smaller than orequal to the area of the main surface of the cathode separator 16.

If the opening area of the first space 60 in the direction parallel tothe main surface of the cathode separator 16 is smaller than the area ofthe main surface of the cathode CA, there is a possibility that aportion of the cathode separator 16 that corresponds to the cathode CAand is not covered with the first space 60 may undergo deformation dueto the hydrogen gas pressure in the cathode CA.

However, in the electrochemical hydrogen pump 100 according to thisembodiment, the entire region of the main surface of the cathode CA canbe covered with the first space 60 by setting the opening area of thefirst space 60 to the area of the main surface of the cathode CA orlarger. Thus, the load is transmitted to the entire region of thecathode separator 16 facing the cathode CA on the basis of the hydrogengas pressure in the first space 60, which can reduce the above-describedpossibility.

EXAMPLES

Specific structures of the first pressure transmitting member will bedescribed below with reference to the drawings.

Example 1

FIG. 4A is a view illustrating an example electrochemical hydrogen pumpin Example 1 according to the first embodiment. In FIG. 4A, a firstpressure transmitting member in a first space 60 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 4A, the first pressure transmittingmember is disposed between a cathode end plate 24C and a cathode platemember 80C and includes columnar members 70C integrated with the cathodeend plate 24C. In this example, the columnar members 70C are disposedbetween the cathode end plate 24C and a cathode insulating plate 23C.Specifically, the columnar members 70C integrated with the cathode endplate 24C are arranged at regular intervals in a planar manner in thefirst space 60, and the end portions of the columnar members 70C are incontact with the cathode insulating plate 23C. The cross-sectional shapeof the columnar members 70C may be circular or rectangular.

In the electrochemical hydrogen pump 100 in Example 1, thisconfiguration enables the pressure from the cathode insulating plate 23Cto be appropriately transmitted to the cathode end plate 24C through thecolumnar members 70C disposed between the cathode end plate 24C and thecathode insulating plate 23C. In the electrochemical hydrogen pump 100in Example 1, hydrogen (H2) can flow through the first space 60 throughvoids present between adjacent columnar members 70C.

The electrochemical hydrogen pump 100 in Example 1 may be the same asthe electrochemical hydrogen pump 100 according to the first embodimentexcept for the foregoing features.

Example 2

FIG. 4B is a view illustrating an example electrochemical hydrogen pumpin Example 2 according to the first embodiment. In FIG. 4B, a firstpressure transmitting member in a first space 60 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 4B, the first pressure transmittingmember is disposed between a cathode end plate 24C and a cathode platemember 80C and includes columnar members 71C separated from the cathodeend plate 24C. In this example, the columnar members 71C are disposedbetween the cathode end plate 24C and a cathode power supply plate 22C.Specifically, the columnar members 71C are arranged at regular intervalsin a planar manner in the first space 60. First end portions of thecolumnar members 71C are in contact with the bottom surface of a recessin a central portion of the cathode end plate 24C, and second endportions are in contact with the cathode power supply plate 22C. Sincethe columnar members 71C are in contact with the cathode end plate 24Cand the cathode power supply plate 22C through an opening in a centralportion of a cathode insulating plate 23C in this example, the columnarmembers 71C are insulating members. This configuration avoids the shortcircuit between the cathode end plate 24C and the cathode power supplyplate 22C. The cross-sectional shape of the columnar members 71C may becircular or rectangular.

In the electrochemical hydrogen pump 100 in Example 2, thisconfiguration enables the pressure from the cathode power supply plate22C to be appropriately transmitted to the cathode end plate 24C throughthe insulating columnar members 71C disposed between the cathode endplate 24C and the cathode power supply plate 22C.

In the electrochemical hydrogen pump 100 in Example 2, hydrogen (H2) canflow through the first space 60 through voids present between adjacentcolumnar members 71C.

In the electrochemical hydrogen pump 100 in Example 2 when includingelastic members as the columnar members 71C, the columnar members 71Cmay expand and contract in response to the deformation of the cathodepower supply plate 22C if the cathode power supply plate 22C undergoesdeformation due to the compression stress of the cathode gas diffusionlayer 14. Thus, the pressure from the cathode power supply plate 22C isuniformly transmitted to the cathode end plate 24C through the columnarmembers 71C.

The electrochemical hydrogen pump 100 in Example 2 may be the same asthe electrochemical hydrogen pump 100 according to the first embodimentexcept for the foregoing features.

Example 3

FIG. 4C is a view illustrating an example electrochemical hydrogen pumpin Example 3 according to the first embodiment. In FIG. 4C, a firstpressure transmitting member in a first space 60 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 4C, the first pressure transmittingmember is disposed between a cathode end plate 24C and a cathode platemember 80C and includes columnar members 72C separated from the cathodeend plate 24C. In this example, the columnar members 72C are disposedbetween the cathode end plate 24C and a cathode insulating plate 23C.Specifically, the columnar members 72C are arranged at regular intervalsin a planar manner in the first space 60. First end portions of thecolumnar members 72C are in contact with the bottom surface of a recessin a central portion of the cathode end plate 24C, and second endportions are in contact with the cathode insulating plate 23C.

In the electrochemical hydrogen pump 100 in Example 3, thisconfiguration enables the pressure from the cathode insulating plate 23Cto be appropriately transmitted to the cathode end plate 24C through thecolumnar members 72C disposed between the cathode end plate 24C and thecathode insulating plate 23C.

In the electrochemical hydrogen pump 100 in Example 3, hydrogen (H2) canflow through the first space 60 through voids present between adjacentcolumnar members 72C.

In the electrochemical hydrogen pump 100 in Example 3 when includingelastic members as the columnar members 72C, the columnar members 72Cmay expand and contract in response to the deformation of the cathodeinsulating plate 23C if the cathode insulating plate 23C undergoesdeformation due to the compression stress of the cathode gas diffusionlayer 14. Thus, the pressure from the cathode insulating plate 23C isuniformly transmitted to the cathode end plate 24C through the columnarmembers 72C.

The electrochemical hydrogen pump 100 in Example 3 may be the same asthe electrochemical hydrogen pump 100 according to the first embodimentexcept for the foregoing features.

Example 4

FIG. 4D is a view illustrating an example electrochemical hydrogen pumpin Example 4 according to the first embodiment. In FIG. 4D, a firstpressure transmitting member in a first space 60 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 4D, the first pressure transmittingmember includes a porous member 73C. The first pressure transmittingmember has any structure as long as it includes the porous member 73C.

For example, as illustrated in FIG. 4D, the porous member 73C having aplate shape is disposed in substantially the entire region in a recess(first space 60) in a central portion of a cathode end plate 24C. Afirst main surface of the porous member 73C is in contact with thebottom surface of the recess, and a second main surface of the porousmember 73C is in contact with the main surface of the cathode insulatingplate 23C.

Examples of the base material of the porous member 73C include the basematerial of the anode gas diffusion layer 15. In other words, in thiscase, the first pressure transmitting member has rigidity as high as theanode gas diffusion layer 15 included in the anode AN. Since the firstpressure transmitting member has high rigidity, the pressure from thecathode plate member 80C can suppress the displacement of the firstpressure transmitting member and can further suppress the displacementof the cathode plate member 80C toward the first space 60.

In the electrochemical hydrogen pump 100 in Example 4, thisconfiguration enables the pressure from the cathode insulating plate 23Cto be appropriately transmitted to the cathode end plate 24C through theporous member 73C disposed between the cathode end plate 24C and thecathode insulating plate 23C. In particular, since the pressure from thecathode insulating plate 23C is transmitted to the cathode end plate 24Cthrough substantially the entire main surface of the porous member 73Cin the electrochemical hydrogen pump 100 in Example 4, the bending ofthe cathode insulating plate 23C toward the cathode end plate 24C can besuppressed effectively. This configuration can suppress extension of thecathode gas diffusion layer 14 toward the cathode end plate 24C.

In the electrochemical hydrogen pump 100 in Example 4, the use of theporous member 73C as the first pressure transmitting member canappropriately ensure gas permeability in the first space 60 even whenthe porous member 73C is disposed in substantially the entire region inthe first space 60, as illustrated in FIG. 4D.

The electrochemical hydrogen pump 100 in Example 4 may be the same asthe electrochemical hydrogen pump 100 according to the first embodimentexcept for the foregoing features.

Example 5

FIG. 4E is a view illustrating an example electrochemical hydrogen pumpin Example 5 according to the first embodiment. In FIG. 4E, a firstpressure transmitting member in a first space 60 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 4E, the first pressure transmittingmember includes an elastic member 74C. The first pressure transmittingmember has any structure as long as it includes the elastic member 74C.

For example, as illustrated in FIG. 4E, the elastic member 74C having aplate shape is disposed in substantially the entire region in a recess(first space 60) in a central portion of a cathode end plate 24C. Afirst main surface of the elastic member 74C is in contact with thebottom surface of the recess, and a second main surface of the elasticmember 74C is in contact with the main surface of the cathode insulatingplate 23C.

Examples of the base material of the elastic member 74C include the basematerial of the cathode gas diffusion layer 14. In other words, in thiscase, the first pressure transmitting member has rigidity as high as thecathode gas diffusion layer 14 included in the cathode CA.

In the electrochemical hydrogen pump 100 in Example 5, thisconfiguration enables the pressure from the cathode insulating plate 23Cto be appropriately transmitted to the cathode end plate 24C through theelastic member 74C disposed between the cathode end plate 24C and thecathode insulating plate 23C. In particular, since the pressure from thecathode insulating plate 23C is transmitted to the cathode end plate 24Cthrough substantially the entire main surface of the elastic member 74Cin the electrochemical hydrogen pump 100 in Example 5, the bending ofthe cathode insulating plate 23C toward the cathode end plate 24C can besuppressed effectively.

In the electrochemical hydrogen pump 100 in Example 5 including theelastic member 74C as the first pressure transmitting member, theelastic member 74C may conform to the deformation of the cathodeinsulating plate 23C if the cathode insulating plate 23C undergoesdeformation due to the compression stress of the cathode gas diffusionlayer 14. Thus, the pressure from the cathode insulating plate 23C isuniformly transmitted to the cathode end plate 24C through the elasticmember 74C.

In the electrochemical hydrogen pump 100 in Example 5, the deformationof the cathode insulating plate 23C due to the compression stress of thecathode gas diffusion layer 14 is suppressed by the reaction forcegenerated by the elastic deformation that occurs in the direction inwhich the thickness of the elastic member 74C having the same elasticmodulus as the cathode gas diffusion layer 14 decreases. In other words,the amount of elastic deformation of the cathode gas diffusion layer 14is substantially equal to the amount of elastic deformation of theelastic member 74C. The foregoing reaction force can be thus maintainedappropriately when the cathode gas diffusion layer 14 elasticallydeforms in the direction in which the thickness after compressionreturns to the thickness before compression as the hydrogen pressureincreasing operation of the electrochemical hydrogen pump 100 proceeds.

The electrochemical hydrogen pump 100 in Example 5 may be the same asthe electrochemical hydrogen pump 100 according to the first embodimentexcept for the foregoing features.

Modifications

In the electrochemical hydrogen pump 100 according to this embodiment,the first space 60 is formed by a recess in a central portion of thecathode end plate 24C. However, the first space 60 is illustrative, andthe present invention is not limited to this example. Other examples ofthe first space will be described below with reference to the drawings.

Modification 1

FIG. 5A is a view illustrating an example electrochemical hydrogen pumpin Modification 1 according to the first embodiment. In FIG. 5A, a firstspace 61 disposed between a cathode end plate 24C and a cathodeseparator 16 positioned in a second end is depicted.

In the example illustrated in FIG. 5A, the first space 61 is formed by arecess in a central portion of the cathode separator 16 and disposed ina contact section between the cathode separator 16 and a cathode powersupply plate 22C. In other words, the first space 61 is defined by therecess in the central portion of the cathode separator 16 and thecathode power supply plate 22C.

In the first space 61, a first pressure transmitting member thattransmits a pressure from the cathode separator 16 to the cathode endplate 24C is disposed. Specific examples of the first pressuretransmitting member are the same as those in the electrochemicalhydrogen pumps 100 in Example 1 to Example 5 according to the firstembodiment, and description of specific examples is thus omitted. Theoperation and effect of the electrochemical hydrogen pump 100 inModification 1 are the same as the operation and effect of theelectrochemical hydrogen pump 100 according to the first embodiment, anddetailed description of the operation and effect is thus omitted.

The electrochemical hydrogen pump 100 in Modification 1 may be the sameas the electrochemical hydrogen pump 100 according to any one of thefirst embodiment and Example 1 to Example 5 according to the firstembodiment except for the foregoing features.

Modification 2

FIG. 5B is a view illustrating an example electrochemical hydrogen pumpin Modification 2 according to the first embodiment. In FIG. 5B, a firstspace 62 disposed between a cathode end plate 24C and a cathodeseparator 16 positioned in a second end is depicted.

In the example illustrated in FIG. 5B, the first space 62 is formed by arecess in a central portion of a cathode power supply plate 22C and anopening in a central portion of a cathode insulating plate 23C. In otherwords, the first space 62 is defined by the recess in the centralportion of the cathode power supply plate 22C, the opening in thecentral portion of the cathode insulating plate 23C, and the cathode endplate 24C.

In the first space 62, a first pressure transmitting member thattransmits a pressure from the cathode separator 16 to the cathode endplate 24C is disposed. Specific examples of the first pressuretransmitting member are the same as those in the electrochemicalhydrogen pumps 100 in Example 1 to Example 5 according to the firstembodiment, and description of specific examples is thus omitted. Sincethe first pressure transmitting member is in contact with the cathodeend plate 24C and the cathode power supply plate 22C through the openingin the central portion of the cathode insulating plate 23C in thisexample, the first pressure transmitting member is an insulating member.This configuration avoids the short circuit between the cathode endplate 24C and the cathode power supply plate 22C.

The operation and effect of the electrochemical hydrogen pump 100 inModification 2 are the same as the operation and effect of theelectrochemical hydrogen pump 100 according to the first embodiment, anddetailed description of the operation and effect is thus omitted.

The electrochemical hydrogen pump 100 in Modification 2 may be the sameas the electrochemical hydrogen pump 100 according to any one of thefirst embodiment and Example 1 to Example 5 according to the firstembodiment except for the foregoing features.

Modification 3

FIG. 5C is a view illustrating an example electrochemical hydrogen pumpin Modification 3 according to the first embodiment. In FIG. 5C, a firstspace 63 disposed between a cathode end plate 24C and a cathodeseparator 16 positioned in a second end is depicted.

In the example illustrated in FIG. 5C, the first space 63 is formed by arecess in a central portion of a cathode power supply plate 22C. Inother words, the first space 63 is defined by the recess in the centralportion of the cathode power supply plate 22C and a cathode insulatingplate 23C.

In the first space 63, a first pressure transmitting member thattransmits a pressure from the cathode separator 16 to the cathode endplate 24C is disposed. Specific examples of the first pressuretransmitting member are the same as those in the electrochemicalhydrogen pumps 100 in Example 1 to Example 5 according to the firstembodiment, and description of specific examples is thus omitted. Theoperation and effect of the electrochemical hydrogen pump 100 inModification 3 are the same as the operation and effect of theelectrochemical hydrogen pump 100 according to the first embodiment, anddetailed description of the operation and effect is thus omitted.

The electrochemical hydrogen pump 100 in Modification 3 may be the sameas the electrochemical hydrogen pump 100 according to any one of thefirst embodiment and Example 1 to Example 5 according to the firstembodiment except for the foregoing features.

Second Embodiment

FIG. 6 is a view illustrating an example electrochemical hydrogen pumpaccording to a second embodiment.

FIG. 6 illustrates the vertical cross-section of an electrochemicalhydrogen pump 100 including a straight line that passes through thecenter of the electrochemical hydrogen pump 100 and the center of acathode gas outlet manifold 50 in plan view.

The electrochemical hydrogen pump 100 according to this embodiment isthe same as the electrochemical hydrogen pump 100 according to the firstembodiment except for the arrangement position of a cathode gas outletchannel 26A described below.

In the electrochemical hydrogen pump 100 according to this embodiment,the cathode gas outlet channel 26A is guided so as to extend from thecathode gas outlet manifold 50 instead of being guided so as to extendfrom the inside of the first space 60 like the cathode gas outletchannel 26 illustrated in FIG. 2A.

In this case, the cathode gas outlet manifold 50 is formed by connectionof through-holes in the members of the hydrogen pump unit 100A and thecathode end plate 24C and a non-through hole in the anode end plate 24A.

Accordingly, in the electrochemical hydrogen pump 100 according to thisembodiment, high-pressure hydrogen generated in the cathode CA of thehydrogen pump unit 100A can be supplied to the first space 60 disposedbetween the cathode end plate 24C and the cathode separator 16 throughthe cathode gas outlet manifold 50 and the cathode gas supply channel51. In other words, high-pressure hydrogen is retained in the firstspace 60.

The operation and effect of the electrochemical hydrogen pump 100according to this embodiment are the same as the operation and effect ofthe electrochemical hydrogen pump 100 according to the first embodiment,and detailed description of the operation and effect is thus omitted.

The electrochemical hydrogen pump 100 according to this embodiment maybe the same as the electrochemical hydrogen pump 100 according to anyone of the first embodiment, Example 1 to Example 5 according to thefirst embodiment, and Modification 1 to Modification 3 according to thefirst embodiment, except for the foregoing features.

Third Embodiment

FIG. 7 is a view illustrating an example electrochemical hydrogen pumpaccording to a third embodiment.

FIG. 7 illustrates the vertical cross-section of an electrochemicalhydrogen pump 100 including a straight line that passes through thecenter of the electrochemical hydrogen pump 100 and the center of acathode gas outlet manifold 50 in plan view.

The electrochemical hydrogen pump 100 according to this embodiment isthe same as the electrochemical hydrogen pump 100 according to the firstembodiment except that the electrochemical hydrogen pump 100 accordingto this embodiment includes a second space 65, a second gas flowchannel, and a second pressure transmitting member described below.

As illustrated in FIG. 7 , the electrochemical hydrogen pump 100includes the second gas flow channel through which hydrogen generated inthe cathode CA (see FIG. 2B) is supplied to the second space 65 disposedbetween an anode end plate 24A and an anode separator 17 positioned inthe first end.

The second space 65 has any feature as long as the second space 65 isdisposed between the anode end plate 24A and the anode separator 17positioned in the first end. In the example illustrated in FIG. 7 , thesecond space 65 is formed by a recess in a central portion of the anodeend plate 24A. In other words, the second space 65 is defined by therecess in the central portion of the anode end plate 24A and the anodeinsulating plate 23A. Other examples of the second space will bedescribed in Modifications.

In the electrochemical hydrogen pump 100 according to this embodiment, asecond pressure transmitting member is provided in the second space 65as indicated by the arrows in FIG. 7 . The second pressure transmittingmember may have any structure as long as it can transmit a pressure fromthe anode separator 17 positioned in the first end to the anode endplate 24A. Specific structures of the second pressure transmittingmember will be described in Examples.

The second gas flow channel may have any structure as long as hydrogengenerated in the cathode CA can be supplied to the second space 65through the second gas flow channel. For example, in the electrochemicalhydrogen pump 100 according to this embodiment, as illustrated in FIG. 7, the second gas flow channel includes a tubular cathode gas outletmanifold 50 and a cathode gas supply channel 52 through which thecathode gas outlet manifold 50 is in communication with the second space65.

The cathode gas outlet manifold 50 is formed by connection ofthrough-holes in the members of the hydrogen pump unit 100A andnon-through holes in the anode end plate 24A and the cathode end plate24C, as in the first embodiment.

The cathode gas supply channel 52 is formed by a groove that is providedin the main surface of the anode end plate 24A and through which theinside of the recess (second space 65) of the anode end plate 24A is incommunication with a first end portion of the cathode gas outletmanifold 50.

In the electrochemical hydrogen pump 100 according to this embodimenthaving this configuration, the increase of contact resistance betweenthe cathode gas diffusion layer 14 and the electrolyte membrane 11(cathode catalyst layer 12) in the hydrogen pump unit 100A when the gaspressure of the cathode CA increases is suppressed in the followingmanner.

On the basis of the hydrogen gas pressure in the cathode CA of thehydrogen pump unit 100A, a load is transmitted to the anode AN and theanode separator 17. When the hydrogen gas pressure in the cathode CA ofthe hydrogen pump unit 100A is high, the anode separator 17 may bedeformed by being pressed outward under this load. If the elasticdeformation in the direction in which the thickness of the cathode gasdiffusion layer 14 increases cannot conform to the deformation of theanode separator 17, a gap may be generated between the cathode gasdiffusion layer 14 and the electrolyte membrane 11 (cathode catalystlayer 12) of the hydrogen pump unit 100A. As a result, the contactresistance between the cathode gas diffusion layer 14 and theelectrolyte membrane 11 (cathode catalyst layer 12) of the hydrogen pumpunit 100A may increase.

However, in the electrochemical hydrogen pump 100 according to thisembodiment, high-pressure hydrogen generated in the cathode CA of thehydrogen pump unit 100A can be supplied to the second space 65 disposedbetween the anode end plate 24A and the anode separator 17 through thecathode gas outlet manifold 50 and the cathode gas supply channel 52.Therefore, the hydrogen gas pressure in the second space 65 issubstantially the same as the hydrogen gas pressure in the cathode CA ofthe hydrogen pump unit 100A. The load applied to the anode separator 17by hydrogen in the second space 65 acts so as to prevent or reduce thedeformation of the anode separator 17 due to the hydrogen gas pressurein the cathode CA. Since a gap is unlikely to form between the cathodegas diffusion layer 14 and the electrolyte membrane 11 (cathode catalystlayer 12) of the hydrogen pump unit 100A in the electrochemical hydrogenpump 100 according to this embodiment compared with the case without thesecond space 65, the increase of contact resistance between the cathodegas diffusion layer 14 and the electrolyte membrane 11 (cathode catalystlayer 12) can be suppressed appropriately.

In the electrochemical hydrogen pump 100 according to this embodiment,the increase of contact resistance between the cathode gas diffusionlayer 14 and the electrolyte membrane 11 (cathode catalyst layer 12) ofthe hydrogen pump unit due to the compression stress of the cathode gasdiffusion layer 14 acting on the anode separator 17 can be suppressed inthe following manner.

In the elastic deformation in the direction in which the thickness ofthe cathode gas diffusion layer 14 decreases, the compression stress ofthe cathode gas diffusion layer 14 acts through the cathode catalystlayer 12, the electrolyte membrane 11, the anode catalyst layer 13, andthe anode gas diffusion layer 15 in the direction in which the anodeseparator 17 is pressed toward the second space 65. If the secondpressure transmitting member that transmits a pressure from the anodeseparator 17 to the anode end plate 24A is not disposed in the secondspace 65, the anode separator 17 tends to bend toward the anode endplate 24A. If the elastic deformation in the direction in which thethickness of the cathode gas diffusion layer 14 increases cannot conformto the deformation of the anode separator 17, a gap may be generatedbetween the cathode gas diffusion layer 14 and the electrolyte membrane11 (cathode catalyst layer 12) of the hydrogen pump unit 100A. As aresult, the contact resistance between the cathode gas diffusion layer14 and the electrolyte membrane 11 (cathode catalyst layer 12) of thehydrogen pump unit 100A may increase.

However, in the electrochemical hydrogen pump 100 according to thisembodiment, the disposition of, in the second space 65, the secondpressure transmitting member that transmits a pressure from the anodeseparator 17 to the anode end plate 24A, as described above, makes itdifficult for the anode separator 17 to bend toward the anode end plate24A in the elastic deformation in the direction in which the thicknessof the cathode gas diffusion layer 14 decreases. Since a gap is unlikelyto form between the cathode gas diffusion layer 14 and the electrolytemembrane 11 (cathode catalyst layer 12) of the hydrogen pump unit 100Ain the electrochemical hydrogen pump 100 according to this embodimentcompared with the case without the second pressure transmitting memberin the second space 65, the increase of contact resistance between thecathode gas diffusion layer 14 and the electrolyte membrane 11 (cathodecatalyst layer 12) can be suppressed appropriately.

In the case where the electrolyte membrane 11 is, for example, a polymerelectrolyte membrane, the polymer electrolyte membrane exhibits desiredproton conductivity in the wet condition. To maintain the efficiency ofthe hydrogen pressure increasing operation of the electrochemicalhydrogen pump 100 at a desired value, the electrolyte membrane 11 needsto be kept wet. If the anode gas flow channel 33 (see FIG. 2B) of theanode separator 17 or the like is blocked with water in this case, thehydrogen supply of the hydrogen pump unit 100A is inhibited. In otherwords, a stable flow of hydrogen passing through the anode gas flowchannel 33 is an important factor for efficient hydrogen pressureincreasing operation of the electrochemical hydrogen pump 100. From sucha viewpoint, in the electrochemical hydrogen pump 100 according to thisembodiment, the anode separator 17 is unlikely to deform regardless ofthe gas pressure of hydrogen generated in the cathode CA of the hydrogenpump unit 100A, which can appropriately stabilize the flow of hydrogenpassing through the anode gas flow channel 33 of the anode separator 17,compared with the case without the second space 65 and the case withoutthe second pressure transmitting member in the second space 65.

In the example illustrated in FIG. 7 , the first space 60 is situatedopposite to the second space 65 in the electrochemical hydrogen pump100.

With this configuration, the load applied to the cathode separator 16 byhydrogen in the first space 60 and the load applied to the anodeseparator 17 by hydrogen in the second space 65 act so as to uniformlysuppress, in the plane from the opposite end portions of the hydrogenpump unit 100A, the deformation of the members of the hydrogen pump unit100A due to the hydrogen gas pressure in the cathode CA.

Therefore, in the electrochemical hydrogen pump 100 according to thisembodiment, the deformation of the members of the hydrogen pump unit100A can be effectively suppressed compared with the case where thefirst space 60 is not situated opposite to the second space 65.

In the example illustrated in FIG. 7 , the second space 65 is parallelto the main surface of the anode AN (see FIG. 2B) in the electrochemicalhydrogen pump 100.

The load transmitted to the anode separator 17 can be thus uniformlydistributed in the plane of the anode separator 17 on the basis of thehydrogen gas pressure in the second space 65. Therefore, theelectrochemical hydrogen pump 100 according to this embodimenteffectively operates in such a manner that the load applied to the anodeseparator 17 by hydrogen in the second space 65 prevents or reducesdeformation (bending) of the anode separator 17 compared with the casewhere the second space 65 is not parallel to the main surface of theanode AN.

In the example illustrated in FIG. 7 , the opening area of the secondspace 65 in the direction parallel to the main surface of the anodeseparator 17 in the electrochemical hydrogen pump 100 is larger than orequal to the area of the main surface of the anode AN (see FIG. 2B).However, the opening area of such a second space 65 is smaller than orequal to the area of the main surface of the anode separator 17.

If the opening area of the second space 65 in the direction parallel tothe main surface of the anode separator 17 is smaller than the area ofthe main surface of the anode AN, there is a possibility that a portionof the anode separator 17 that faces the anode AN and is not coveredwith the second space 65 may undergo deformation due to the hydrogen gaspressure in the cathode CA.

However, in the electrochemical hydrogen pump 100 according to thisembodiment, the entire region of the main surface of the anode AN can becovered with the second space 65 by setting the opening area of thesecond space 65 to the area of the main surface of the anode AN orlarger. Thus, the load is transmitted to the entire region of the anodeseparator 17 facing the anode AN on the basis of the hydrogen gaspressure in the second space 65, which can reduce the above-describedpossibility.

The electrochemical hydrogen pump 100 according to this embodiment maybe the same as the electrochemical hydrogen pump 100 according to anyone of the first embodiment, Example 1 to Example 5 according to thefirst embodiment, Modification 1 to Modification 3 according to thefirst embodiment, and the second embodiment, except for the foregoingfeatures.

EXAMPLES

Specific structures of the second pressure transmitting member will bedescribed below with reference to the drawings.

Example 1

FIG. 8A is a view illustrating an example electrochemical hydrogen pumpin Example 1 according to the third embodiment. In FIG. 8A, a secondpressure transmitting member in a second space 65 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 8A, the second pressure transmittingmember is disposed between an anode end plate 24A and an anode platemember 80A and includes columnar members 70A integrated with the anodeend plate 24A. In this example, the columnar members 70A are disposedbetween the anode end plate 24A and an anode insulating plate 23A.Specifically, the columnar members 70A integrated with the anode endplate 24A are arranged at regular intervals in a planar manner in thesecond space 65, and the end portions of the columnar members 70A are incontact with the anode insulating plate 23A. The cross-sectional shapeof the columnar members 70A may be circular or rectangular.

In the electrochemical hydrogen pump 100 in Example 1, thisconfiguration enables the pressure from the anode insulating plate 23Ato be appropriately transmitted to the anode end plate 24A through thecolumnar members 70A disposed between the anode end plate 24A and theanode insulating plate 23A. In the electrochemical hydrogen pump 100 inExample 1, hydrogen (H2) can be retained in voids present betweenadjacent columnar members 70A in the second space 65.

The electrochemical hydrogen pump 100 according to Example 1 may be thesame as the electrochemical hydrogen pump 100 according to any one ofthe first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, and the third embodiment, except forthe foregoing features.

Example 2

FIG. 8B is a view illustrating an example electrochemical hydrogen pumpin Example 2 according to the third embodiment. In FIG. 8B, a secondpressure transmitting member in a second space 65 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 8B, the second pressure transmittingmember is disposed between an anode end plate 24A and an anode platemember 80A and includes columnar members 71A separated from the anodeend plate 24A. In this example, columnar members 71A are disposedbetween the anode end plate 24A and an anode power supply plate 22A.Specifically, the columnar members 71A are arranged at regular intervalsin a planar manner in the second space 65. First end portions of thecolumnar members 71A are in contact with the bottom surface of a recessin a central portion of the anode end plate 24A, and second end portionsare in contact with the anode power supply plate 22A. Since the columnarmembers 71A are in contact with the anode end plate 24A and the anodepower supply plate 22A through an opening in a central portion of ananode insulating plate 23A in this example, the columnar members 71A areinsulating members. This configuration avoids the short circuit betweenthe anode end plate 24A and the anode power supply plate 22A. Thecross-sectional shape of the columnar members 71A may be circular orrectangular.

In the electrochemical hydrogen pump 100 in Example 2, thisconfiguration enables the pressure from the anode power supply plate 22Ato be appropriately transmitted to the anode end plate 24A through theinsulating columnar members 71A disposed between the anode end plate 24Aand the anode power supply plate 22A.

In the electrochemical hydrogen pump 100 in Example 2, hydrogen (H2) canbe retained in voids present between adjacent columnar members 71A inthe second space 65.

In the electrochemical hydrogen pump 100 in Example 2 when includingelastic members as the columnar members 71A, the columnar members 71Amay expand and contract in response to the deformation of the anodepower supply plate 22A if the anode power supply plate 22A undergoesdeformation due to the compression stress of the cathode gas diffusionlayer 14. Thus, the pressure from the anode power supply plate 22A isuniformly transmitted to the anode end plate 24A through the columnarmembers 71A.

The electrochemical hydrogen pump 100 according to Example 2 may be thesame as the electrochemical hydrogen pump 100 according to any one ofthe first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, and the third embodiment, except forthe foregoing features.

Example 3

FIG. 8C is a view illustrating an example electrochemical hydrogen pumpin Example 3 according to the third embodiment. In FIG. 8C, a secondpressure transmitting member in a second space 65 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 8C, the second pressure transmittingmember is disposed between an anode end plate 24A and an anode platemember 80A and includes columnar members 72A separated from the anodeend plate 24A. In this example, the columnar members 72A are disposedbetween the anode end plate 24A and an anode insulating plate 23A.Specifically, the columnar members 72A are arranged at regular intervalsin a planar manner in the second space 65. First end portions of thecolumnar members 72A are in contact with the bottom surface of a recessin a central portion of the anode end plate 24A, and second end portionsare in contact with the anode insulating plate 23A.

In the electrochemical hydrogen pump 100 in Example 3, thisconfiguration enables the pressure from the anode insulating plate 23Ato be appropriately transmitted to the anode end plate 24A through thecolumnar members 72A disposed between the anode end plate 24A and theanode insulating plate 23A.

In the electrochemical hydrogen pump 100 in Example 3, hydrogen (H2) canbe retained in voids present between adjacent columnar members 72A inthe second space 65.

In the electrochemical hydrogen pump 100 in Example 3 when includingelastic members as the columnar members 72A, the columnar members 72Amay expand and contract in response to the deformation of the anodeinsulating plate 23A if the anode insulating plate 23A undergoesdeformation due to the compression stress of the cathode gas diffusionlayer 14. Thus, the pressure from the anode insulating plate 23A isuniformly transmitted to the anode end plate 24A through the columnarmembers 72A.

The electrochemical hydrogen pump 100 according to Example 3 may be thesame as the electrochemical hydrogen pump 100 according to any one ofthe first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, and the third embodiment, except forthe foregoing features.

Example 4

FIG. 8D is a view illustrating an example electrochemical hydrogen pumpin Example 4 according to the third embodiment. In FIG. 8D, a secondpressure transmitting member in a second space 65 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 8D, the second pressure transmittingmember includes a porous member 73A. The second pressure transmittingmember has any structure as long as it includes the porous member 73A.

For example, as illustrated in FIG. 8D, the porous member 73A having aplate shape is disposed in substantially the entire region in a recess(second space 65) in a central portion of an anode end plate 24A. Afirst main surface of the porous member 73A is in contact with thebottom surface of the recess, and a second main surface of the porousmember 73A is in contact with the main surface of the anode insulatingplate 23A.

Examples of the base material of the porous member 73A include the basematerial of the anode gas diffusion layer 15. In other words, in thiscase, the second pressure transmitting member has rigidity as high asthe anode gas diffusion layer 15 included in the anode AN.

In the electrochemical hydrogen pump 100 in Example 4, thisconfiguration enables the pressure from the anode insulating plate 23Ato be appropriately transmitted to the anode end plate 24A through theporous member 73A disposed between the anode end plate 24A and the anodeinsulating plate 23A. In particular, since the pressure from the anodeinsulating plate 23A is transmitted to the anode end plate 24A throughsubstantially the entire main surface of the porous member 73A in theelectrochemical hydrogen pump 100 in Example 4, the bending of the anodeinsulating plate 23A toward the anode end plate 24A can be suppressedeffectively.

In the electrochemical hydrogen pump 100 in Example 4, the use of theporous member 73A as the second pressure transmitting member canappropriately ensure gas permeability in the second space 65 even whenthe porous member 73A is disposed in substantially the entire region inthe second space 65, as illustrated in FIG. 8D.

The electrochemical hydrogen pump 100 according to Example 4 may be thesame as the electrochemical hydrogen pump 100 according to any one ofthe first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, and the third embodiment, except forthe foregoing features.

Example 5

FIG. 8E is a view illustrating an example electrochemical hydrogen pumpin Example 5 according to the third embodiment. In FIG. 8E, a secondpressure transmitting member in a second space 65 of an electrochemicalhydrogen pump 100 is depicted.

In the example illustrated in FIG. 8E, the second pressure transmittingmember includes an elastic member 74A. The second pressure transmittingmember has any structure as long as it includes the elastic member 74A.

For example, as illustrated in FIG. 8E, the elastic member 74A having aplate shape is disposed in substantially the entire region in a recess(second space 65) in a central portion of an anode end plate 24A. Afirst main surface of the elastic member 74A is in contact with thebottom surface of the recess, and a second main surface of the elasticmember 74A is in contact with the main surface of the anode insulatingplate 23A.

Examples of the base material of the elastic member 74A include the basematerial of the cathode gas diffusion layer 14. In other words, in thiscase, the second pressure transmitting member has rigidity as high asthe cathode gas diffusion layer 14 included in the cathode CA.

In the electrochemical hydrogen pump 100 in Example 5, thisconfiguration enables the pressure from the anode insulating plate 23Ato be appropriately transmitted to the anode end plate 24A through theelastic member 74A disposed between the anode end plate 24A and theanode insulating plate 23A. In particular, since the pressure from theanode insulating plate 23A is transmitted to the anode end plate 24Athrough substantially the entire main surface of the elastic member 74Ain the electrochemical hydrogen pump 100 in Example 5, the bending ofthe anode insulating plate 23A toward the anode end plate 24A can besuppressed effectively.

In the electrochemical hydrogen pump 100 in Example 5 including theelastic member 74A as the second pressure transmitting member, theelastic member 74A may conform to the deformation of the anodeinsulating plate 23A if the anode insulating plate 23A is deformed bythe compression stress of the cathode gas diffusion layer 14. As aresult, the pressure from the anode insulating plate 23A is uniformlytransmitted to the anode end plate 24A through the elastic member 74A.

In the electrochemical hydrogen pump 100 in Example 5, the deformationof the anode insulating plate 23A due to the compression stress of thecathode gas diffusion layer 14 is suppressed by the reaction forcegenerated by the elastic deformation that occurs in the direction inwhich the thickness of the elastic member 74A having the same elasticmodulus as the cathode gas diffusion layer 14 decreases. In other words,the amount of elastic deformation of the cathode gas diffusion layer 14is substantially equal to the amount of elastic deformation of theelastic member 74A. The foregoing reaction force can be thus maintainedappropriately when the cathode gas diffusion layer 14 elasticallydeforms in the direction in which the thickness after compressionreturns to the thickness before compression as the hydrogen pressureincreasing operation of the electrochemical hydrogen pump 100 proceeds.

The electrochemical hydrogen pump 100 according to Example 5 may be thesame as the electrochemical hydrogen pump 100 according to any one ofthe first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, and the third embodiment, except forthe foregoing features.

Modifications

In the electrochemical hydrogen pump 100 according to the thirdembodiment, the second space 65 is formed by a recess in a centralportion of the anode end plate 24A. However, the second space 65 isillustrative, and the present invention is not limited to this example.Other examples of the second space will be described below withreference to the drawings.

Modification 1

FIG. 9A is a view illustrating an example electrochemical hydrogen pumpin Modification 1 according to the third embodiment. In FIG. 9A, asecond space 66 disposed between an anode end plate 24A and an anodeseparator 17 positioned in a first end is depicted.

In the example illustrated in FIG. 9A, the second space 66 is formed bya recess in a central portion of the anode separator 17 and disposed ina contact section between the anode separator 17 and an anode powersupply plate 22A. In other words, the second space 66 is defined by therecess in the central portion of the anode separator 17 and the anodepower supply plate 22A.

In the second space 66, a second pressure transmitting member thattransmits a pressure from the anode separator 17 to the anode end plate24A is disposed. Specific examples of the second pressure transmittingmember are the same as those in the electrochemical hydrogen pumps 100in Example 1 to Example 5 according to the third embodiment, anddescription of specific examples is thus omitted. The operation andeffect of the electrochemical hydrogen pump 100 in Modification 1 arethe same as the operation and effect of the electrochemical hydrogenpump 100 according to the third embodiment, and detailed description ofthe operation and effect is thus omitted.

The electrochemical hydrogen pump 100 according to Modification 1 may bethe same as the electrochemical hydrogen pump 100 according to any oneof the first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, the third embodiment, and Example 1to Example 5 according to the third embodiment, except for the foregoingfeatures.

Modification 2

FIG. 9B is a view illustrating an example electrochemical hydrogen pumpin Modification 2 according to the third embodiment. In FIG. 9B, asecond space 67 disposed between an anode end plate 24A and an anodeseparator 17 positioned in a first end is depicted.

In the example illustrated in FIG. 9B, the second space 67 is formed bya recess in a central portion of an anode power supply plate 22A and anopening in a central portion of an anode insulating plate 23A. In otherwords, the second space 67 is defined by the recess in the centralportion of the anode power supply plate 22A, the opening in the centralportion of the anode insulating plate 23A, and the anode end plate 24A.

In the second space 67, a second pressure transmitting member thattransmits a pressure from the anode separator 17 to the anode end plate24A is disposed. Specific examples of the second pressure transmittingmember are the same as those in the electrochemical hydrogen pumps 100in Example 1 to Example 5 according to the third embodiment, anddescription of specific examples is thus omitted. Since the secondpressure transmitting member is in contact with the anode end plate 24Aand the anode power supply plate 22A through the opening in the centralportion of the anode insulating plate 23A in this example, the firstpressure transmitting member is an insulating member. This configurationavoids the short circuit between the anode end plate 24A and the anodepower supply plate 22A.

The operation and effect of the electrochemical hydrogen pump 100 inModification 2 are the same as the operation and effect of theelectrochemical hydrogen pump 100 according to the third embodiment, anddetailed description of the operation and effect is thus omitted.

The electrochemical hydrogen pump 100 according to Modification 2 may bethe same as the electrochemical hydrogen pump 100 according to any oneof the first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, the third embodiment, and Example 1to Example 5 according to the third embodiment, except for the foregoingfeatures.

Modification 3

FIG. 9C is a view illustrating an example electrochemical hydrogen pumpin Modification 3 according to the third embodiment. In FIG. 9C, asecond space 68 disposed between an anode end plate 24A and an anodeseparator 17 positioned in a first end is depicted.

In the example illustrated in FIG. 9C, the second space 68 is formed bya recess in a central portion of the anode power supply plate 22A. Inother words, the second space 68 is defined by the recess in the centralportion of the anode power supply plate 22A and the anode insulatingplate 23A.

In the second space 68, a second pressure transmitting member thattransmits a pressure from the anode separator 17 to the anode end plate24A is disposed. Specific examples of the second pressure transmittingmember are the same as those in the electrochemical hydrogen pumps 100in Example 1 to Example 5 according to the third embodiment, anddescription of specific examples is thus omitted. The operation andeffect of the electrochemical hydrogen pump 100 in Modification 3 arethe same as the operation and effect of the electrochemical hydrogenpump 100 according to the third embodiment, and detailed description ofthe operation and effect is thus omitted.

The electrochemical hydrogen pump 100 according to Modification 2 may bethe same as the electrochemical hydrogen pump 100 according to any oneof the first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, the third embodiment, and Example 1to Example 5 according to the third embodiment, except for the foregoingfeatures.

Fourth Embodiment

FIG. 10 is a view illustrating an example electrochemical hydrogen pumpaccording to a fourth embodiment.

FIG. 10 illustrates the vertical cross-section of an electrochemicalhydrogen pump 100 including a straight line that passes through thecenter of the electrochemical hydrogen pump 100 and the center of acathode gas outlet manifold 50 in plan view.

The electrochemical hydrogen pump 100 according to this embodiment isthe same as the electrochemical hydrogen pump 100 according to the thirdembodiment except for the structure of the second gas flow channeldescribed below.

In the electrochemical hydrogen pump 100 according to this embodiment,the second gas flow channel includes a communication flow channelthrough which a first space 60 is in communication with a second space65. In this case, it is not necessary to provide the cathode gas supplychannel 52 (see FIG. 7 ) through which the cathode gas outlet manifold50 is in communication with the second space 65.

Specifically, for example, as illustrated in FIG. 10 , a communicationflow channel member 90 passes through the anode end plate 24A andextends so as to reach the second space 65. The communication flowchannel member 90 diverges from a cathode gas outlet pipe 26Bconstituting a cathode gas outlet channel 26. In other words, in theexample illustrated in FIG. 10 , the communication flow channel member90 is a member through which the first space 60 is in communication withthe second space 65. The structure of the communication flow channelmember is not limited to this. For example, the communication flowchannel member may pass through the cathode end plate 24C and the anodeend plate 24A instead of diverging from the cathode gas outlet pipe 26B.

Accordingly, in the electrochemical hydrogen pump 100 according to thisembodiment, high-pressure hydrogen generated in the cathode CA of thehydrogen pump unit 100A can be supplied to the second space 65 disposedbetween the anode end plate 24A and the anode separator 17 through thecommunication flow channel member 90.

The operation and effect of the electrochemical hydrogen pump 100according to this embodiment are the same as the operation and effect ofthe electrochemical hydrogen pump 100 according to the third embodiment,and detailed description of the operation and effect is thus omitted.

The electrochemical hydrogen pump 100 according to this embodiment maybe the same as the electrochemical hydrogen pump 100 according to anyone of the first embodiment, Example 1 to Example 5 according to thefirst embodiment, Modification 1 to Modification 3 according to thefirst embodiment, the second embodiment, the third embodiment, Example 1to Example 5 according to the third embodiment, and Modification 1 toModification 3 according to the third embodiment, except for theforegoing features.

The first embodiment, Example 1 to Example 5 according to the firstembodiment, Modification 1 to Modification 3 according to the firstembodiment, the second embodiment, the third embodiment, Example 1 toExample 5 according to the third embodiment, Modification 1 toModification 3 according to the third embodiment, and the fourthembodiment may be combined with each other unless they exclude eachother.

From the above description, many improvements and other embodiments ofthe present disclosure are apparent to those skilled in the art.Therefore, the above description should be construed as illustrativeonly and is provided for the purpose of teaching those skilled in theart the best modes for carrying out the present disclosure. The detailsof the structure and/or function of the present disclosure can besubstantially modified without departing from the spirit of the presentdisclosure.

One aspect of the present disclosure can be used for an electrochemicalhydrogen pump in which an increase in contact resistance between acathode separator and a cathode in a hydrogen pump unit can beappropriately suppressed, compared with the related art.

What is claimed is:
 1. An electrochemical hydrogen pump comprising: atleast one hydrogen pump unit that includes an electrolyte membrane, ananode disposed on a first main surface of the electrolyte membrane, acathode disposed on a second main surface of the electrolyte membrane,an anode separator stacked on the anode, and a cathode separator stackedon the cathode; an anode end plate that is disposed on the anodeseparator positioned in a first end in a stacking direction; a cathodeend plate that is disposed on the cathode separator positioned in asecond end in the stacking direction, the first end being one end in thestacking direction, the second end being another end in the stackingdirection; a fixing member that prevents at least members from thecathode end plate to the cathode separator positioned in the second endfrom moving in the stacking direction; a first space disposed betweenthe cathode end plate and the cathode separator positioned in the secondend; a first gas flow channel through which hydrogen generated in thecathode is supplied to the first space; a first cathode gas outletchannel in communication with the first space, and a first pressuretransmitting member that is disposed in the first space and transmits apressure from the cathode separator positioned in the second end to thecathode end plate, wherein an entirety of an opening of the firstcathode gas outlet channel at a first space side faces a surface of thefirst pressure transmitting member, and the first pressure transmittingmember is made of a gas diffusible material.
 2. The electrochemicalhydrogen pump according to claim 1, further comprising: a cathode platemember disposed between the cathode end plate and the cathode separatorpositioned in the second end such that the first space is disposedbetween the cathode plate member and the cathode end plate, wherein thefirst pressure transmitting member is disposed between the cathode endplate and the cathode plate member.
 3. The electrochemical hydrogen pumpaccording to claim 2, wherein the fixing member includes a bolt, and thebolt passes through the cathode plate member and the cathode separatorpositioned in the second end.
 4. The electrochemical hydrogen pumpaccording to claim 2, wherein the cathode plate member includes acathode insulating plate, and the first pressure transmitting member isdisposed between the cathode end plate and the cathode insulating plate.5. The electrochemical hydrogen pump according to claim 2, wherein thecathode plate member includes a cathode power supply plate, and thefirst pressure transmitting member is disposed between the cathode endplate and the cathode power supply plate.
 6. The electrochemicalhydrogen pump according to claim 1, wherein the first pressuretransmitting member includes an elastic member.
 7. The electrochemicalhydrogen pump according to claim 1, wherein the fixing member furtherprevents members from the anode end plate to the anode separatorpositioned in the first end from moving in the stacking direction; andthe electrochemical hydrogen pump further comprises: a second gas flowchannel through which hydrogen generated in the cathode is supplied to asecond space disposed between the anode end plate and the anodeseparator positioned in the first end; and a second pressuretransmitting member that is disposed in the second space and transmits apressure from the anode separator positioned in the first end to theanode end plate.
 8. The electrochemical hydrogen pump according to claim7, further comprising: an anode plate member disposed between the anodeend plate and the anode separator positioned in the first end, whereinthe second pressure transmitting member is disposed between the anodeend plate and the anode plate member and includes a columnar memberseparated from or integrated with the anode end plate.
 9. Theelectrochemical hydrogen pump according to claim 8, wherein a boltincluded in the fixing member passes through the anode plate member andthe anode separator positioned in the first end.
 10. The electrochemicalhydrogen pump according to claim 8, wherein the anode plate memberincludes an anode insulating plate, and the columnar member is disposedbetween the anode end plate and the anode insulating plate.
 11. Theelectrochemical hydrogen pump according to claim 8, wherein the anodeplate member includes an anode power supply plate, and the columnarmember is disposed between the anode end plate and the anode powersupply plate.
 12. The electrochemical hydrogen pump according to claim11, wherein the columnar member is an insulating member.
 13. Theelectrochemical hydrogen pump according to claim 7, wherein the secondpressure transmitting member is a porous member.
 14. The electrochemicalhydrogen pump according to claim 7, wherein the second pressuretransmitting member is an elastic member.
 15. The electrochemicalhydrogen pump according to claim 1, wherein the anode includes an anodegas diffusion layer, the cathode includes a cathode gas diffusion layer,and the anode gas diffusion layer has a higher elastic modulus than thecathode gas diffusion layer.
 16. An electrochemical hydrogen pumpcomprising: at least one hydrogen pump unit that includes an electrolytemembrane, an anode disposed on a first main surface of the electrolytemembrane, a cathode disposed on a second main surface of the electrolytemembrane, an anode separator stacked on the anode, and a cathodeseparator stacked on the cathode; an anode end plate that is disposed onthe anode separator positioned in a first end in a stacking direction; acathode end plate that is disposed on the cathode separator positionedin a second end in the stacking direction, the first end being one endin the stacking direction, the second end being another end in thestacking direction; a fixing member that prevents at least members fromthe cathode end plate to the cathode separator positioned in the secondend from moving in the stacking direction; a first space disposedbetween the cathode end plate and the cathode separator positioned inthe second end; a first gas flow channel through which hydrogengenerated in the cathode is supplied to the first space; and a firstpressure transmitting member that is disposed in the first space andtransmits a pressure from the cathode separator positioned in the secondend to the cathode end plate, wherein: the cathode includes a cathodegas diffusion layer, and the first pressure transmitting member has thesame elastic modulus as the cathode gas diffusion layer included in thecathode.
 17. The electrochemical hydrogen pump according to claim 7,wherein the second pressure transmitting member has the same elasticmodulus as the cathode gas diffusion layer included in the cathode. 18.The electrochemical hydrogen pump according to claim 1, wherein: the atleast one hydrogen pump unit is sandwiched between the anode end plateand the cathode end plat, and the fixing member is a fastener thatfastens at least the anode end plate and the cathode end plate togetherwith the at least one hydrogen pump unit.
 19. The electrochemicalhydrogen pump according to claim 1, wherein: the first gas flow channelincludes a cathode gas outlet manifold and a communication pathconnecting the first space and the cathode gas outlet manifold, and acathode gas supplied from a cathode gas channel, which is disposed inthe cathode separator, flows into the cathode gas outlet manifold.